Camry EGR Valve, Code P0401
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From: Jeff Strickland on 28 Mar 2010 13:16 "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message news:homlot$me2$1(a)news.eternal-september.org... > > "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message > news:holl8b$k4k$1(a)news.eternal-september.org... >> >> "Hachiroku ????" <Trueno(a)e86.GTS> wrote in message >> news:holh7v$6jn$1(a)news.eternal-september.org... >>> On Sat, 27 Mar 2010 09:21:42 -0700, Jeff Strickland wrote: >>> >>>> I have a friend with a Camry (an '01, give or take a year), that has >>>> two >>>> codes stored that are both P0401. I'm not sure how the same code can be >>> >>> >>> Common Problems that Trigger the P0401 code: >>> >>> * Restriction in the EGR passages, usually caused by carbon buildup >>> * Lack of proper vacuum or electrical signal to the EGR valve >>> * Lack of proper EGR system feedback to the computer from the: >>> Manifold Absolute Pressure Sensor (MAP) >>> Differential EGR Pressure Feedback Sensor (DPFE) >>> EGR Valve Position Sensor (EVP) >>> EGR Temperature Sensor >>> * The EGR Valve is defective >>> >>> Then, start here: >>> >>> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=EC&P=12 >>> >>> >>> A P401 can point to other things: bad vacuum flow; this happened on my >>> Tercel. Toyota tested the EGR (gratis) and said it was OK. I rectified >>> the >>> issue by putting a switch on the ECM battery wire. Hit the switch, clear >>> the memory, drive the car two driving cycles and repeat. >>> >>> Finally tracked the problem to a clogged vacuum line. At first we >>> thought >>> it was the vacuum sensor (after the EGR) and then found the hose to the >>> sensor was clogged. >>> >>> >>> >> >> I thought the EGR gets dirty and sticks. How do you clean it? >> >> I'm discounting, for now, electrical or vacuum issues ONLY because if the >> problem is a random occurance, this would seem to indicate a stich valve, >> not missing signals or bad vac supply. Electrics or vac issues would be >> less random and more constant. What I don't know at this moment is if the >> problem IS random or not, and that would make a difference, I think. But >> I want to start with cleaning the EGR, but I don't know what cleaner to >> use, or if the valve can be cleaned in place or has to come off to be >> cleaned. >> > > You are way overthinking the problem. I would check the electrical stuff > first since it is easy to check and doesn't involve removal of the EGR > valve. > > When you diagnose a problem, check the stuff that is easy to check first, > then move to the more complicated stuff, in the order of likelihood. > > The EGR valve and tube can become clogged with carbon. After you remove > the valve, dig out what you can with an awl or screwdriver, being careful > not to damage the valve seat. Some solvent may loosen some of the > deposits but make sure the solvent is dry before reinstalling the valve. > -- > I thought that cleaning it WAS doing the easy stuff first.
From: Ray O on 28 Mar 2010 17:33 "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message news:hoo2t3$ln6$1(a)news.eternal-september.org... > > "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message > news:homlot$me2$1(a)news.eternal-september.org... >> >> "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message >> news:holl8b$k4k$1(a)news.eternal-september.org... >>> >>> "Hachiroku ????" <Trueno(a)e86.GTS> wrote in message >>> news:holh7v$6jn$1(a)news.eternal-september.org... >>>> On Sat, 27 Mar 2010 09:21:42 -0700, Jeff Strickland wrote: >>>> >>>>> I have a friend with a Camry (an '01, give or take a year), that has >>>>> two >>>>> codes stored that are both P0401. I'm not sure how the same code can >>>>> be >>>> >>>> >>>> Common Problems that Trigger the P0401 code: >>>> >>>> * Restriction in the EGR passages, usually caused by carbon buildup >>>> * Lack of proper vacuum or electrical signal to the EGR valve >>>> * Lack of proper EGR system feedback to the computer from the: >>>> Manifold Absolute Pressure Sensor (MAP) >>>> Differential EGR Pressure Feedback Sensor (DPFE) >>>> EGR Valve Position Sensor (EVP) >>>> EGR Temperature Sensor >>>> * The EGR Valve is defective >>>> >>>> Then, start here: >>>> >>>> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=EC&P=12 >>>> >>>> >>>> A P401 can point to other things: bad vacuum flow; this happened on my >>>> Tercel. Toyota tested the EGR (gratis) and said it was OK. I rectified >>>> the >>>> issue by putting a switch on the ECM battery wire. Hit the switch, >>>> clear >>>> the memory, drive the car two driving cycles and repeat. >>>> >>>> Finally tracked the problem to a clogged vacuum line. At first we >>>> thought >>>> it was the vacuum sensor (after the EGR) and then found the hose to the >>>> sensor was clogged. >>>> >>>> >>>> >>> >>> I thought the EGR gets dirty and sticks. How do you clean it? >>> >>> I'm discounting, for now, electrical or vacuum issues ONLY because if >>> the problem is a random occurance, this would seem to indicate a stich >>> valve, not missing signals or bad vac supply. Electrics or vac issues >>> would be less random and more constant. What I don't know at this moment >>> is if the problem IS random or not, and that would make a difference, I >>> think. But I want to start with cleaning the EGR, but I don't know what >>> cleaner to use, or if the valve can be cleaned in place or has to come >>> off to be cleaned. >>> >> >> You are way overthinking the problem. I would check the electrical stuff >> first since it is easy to check and doesn't involve removal of the EGR >> valve. >> >> When you diagnose a problem, check the stuff that is easy to check first, >> then move to the more complicated stuff, in the order of likelihood. >> >> The EGR valve and tube can become clogged with carbon. After you remove >> the valve, dig out what you can with an awl or screwdriver, being careful >> not to damage the valve seat. Some solvent may loosen some of the >> deposits but make sure the solvent is dry before reinstalling the valve. >> -- >> > > I thought that cleaning it WAS doing the easy stuff first. > The gaskets on the EGR valve should be replaced when the valve is removed, so just removing it means buying some parts, and messing with the exhaust system tends to provide ample opportunities for stripped fasteners so my preference is to put a meter on an electrical component with the component in place when possible. You can also check EGR operation with the engine idling, which is pretty easy. Provide vacuum directly to the EGR valve with a vacuum pump or bridged directly from the manifold without passing through VSV's, and if the EGR valve is opening, the engine should start to idle poorly and start to stall. If that happens, the EGR valve is not clogged. There are 2 ways to monitor EGR system operation, monitoring EGR exhaust gas temperature with a sensor and monitoring EGR position with a sensor. Rather than try to look up all the different permutations of engine and model year, it would be easier to just know engine and model year before starting research as you need that info anyway. IIRC, the 2002 is a different generation than the 2001. -- Ray O (correct punctuation to reply)
From: Jeff Strickland on 28 Mar 2010 18:51 "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message news:hooi44$hi9$1(a)news.eternal-september.org... > > "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message > news:hoo2t3$ln6$1(a)news.eternal-september.org... >> >> "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message >> news:homlot$me2$1(a)news.eternal-september.org... >>> >>> "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message >>> news:holl8b$k4k$1(a)news.eternal-september.org... >>>> >>>> "Hachiroku ????" <Trueno(a)e86.GTS> wrote in message >>>> news:holh7v$6jn$1(a)news.eternal-september.org... >>>>> On Sat, 27 Mar 2010 09:21:42 -0700, Jeff Strickland wrote: >>>>> >>>>>> I have a friend with a Camry (an '01, give or take a year), that has >>>>>> two >>>>>> codes stored that are both P0401. I'm not sure how the same code can >>>>>> be >>>>> >>>>> >>>>> Common Problems that Trigger the P0401 code: >>>>> >>>>> * Restriction in the EGR passages, usually caused by carbon buildup >>>>> * Lack of proper vacuum or electrical signal to the EGR valve >>>>> * Lack of proper EGR system feedback to the computer from the: >>>>> Manifold Absolute Pressure Sensor (MAP) >>>>> Differential EGR Pressure Feedback Sensor (DPFE) >>>>> EGR Valve Position Sensor (EVP) >>>>> EGR Temperature Sensor >>>>> * The EGR Valve is defective >>>>> >>>>> Then, start here: >>>>> >>>>> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=EC&P=12 >>>>> >>>>> >>>>> A P401 can point to other things: bad vacuum flow; this happened on my >>>>> Tercel. Toyota tested the EGR (gratis) and said it was OK. I rectified >>>>> the >>>>> issue by putting a switch on the ECM battery wire. Hit the switch, >>>>> clear >>>>> the memory, drive the car two driving cycles and repeat. >>>>> >>>>> Finally tracked the problem to a clogged vacuum line. At first we >>>>> thought >>>>> it was the vacuum sensor (after the EGR) and then found the hose to >>>>> the >>>>> sensor was clogged. >>>>> >>>>> >>>>> >>>> >>>> I thought the EGR gets dirty and sticks. How do you clean it? >>>> >>>> I'm discounting, for now, electrical or vacuum issues ONLY because if >>>> the problem is a random occurance, this would seem to indicate a stich >>>> valve, not missing signals or bad vac supply. Electrics or vac issues >>>> would be less random and more constant. What I don't know at this >>>> moment is if the problem IS random or not, and that would make a >>>> difference, I think. But I want to start with cleaning the EGR, but I >>>> don't know what cleaner to use, or if the valve can be cleaned in place >>>> or has to come off to be cleaned. >>>> >>> >>> You are way overthinking the problem. I would check the electrical >>> stuff first since it is easy to check and doesn't involve removal of the >>> EGR valve. >>> >>> When you diagnose a problem, check the stuff that is easy to check >>> first, then move to the more complicated stuff, in the order of >>> likelihood. >>> >>> The EGR valve and tube can become clogged with carbon. After you remove >>> the valve, dig out what you can with an awl or screwdriver, being >>> careful not to damage the valve seat. Some solvent may loosen some of >>> the deposits but make sure the solvent is dry before reinstalling the >>> valve. >>> -- >>> >> >> I thought that cleaning it WAS doing the easy stuff first. >> > > The gaskets on the EGR valve should be replaced when the valve is removed, > so just removing it means buying some parts, and messing with the exhaust > system tends to provide ample opportunities for stripped fasteners so my > preference is to put a meter on an electrical component with the component > in place when possible. > > You can also check EGR operation with the engine idling, which is pretty > easy. Provide vacuum directly to the EGR valve with a vacuum pump or > bridged directly from the manifold without passing through VSV's, and if > the EGR valve is opening, the engine should start to idle poorly and start > to stall. If that happens, the EGR valve is not clogged. > > There are 2 ways to monitor EGR system operation, monitoring EGR exhaust > gas temperature with a sensor and monitoring EGR position with a sensor. > Rather than try to look up all the different permutations of engine and > model year, it would be easier to just know engine and model year before > starting research as you need that info anyway. IIRC, the 2002 is a > different generation than the 2001. > -- > That's the kind of thing I needed to know. Thanks. I was thinking the problem was one those transient kinds of things, and would not happen again very soon. If I'm wrong, then I will be looking at this car in the not too distant future. The woman said the light had been on for a long time -- many months. She assumed that it needed an O2 Sensor but lacks the money to buy one or to visit a mechanic. Since the car runs fine, she ignored the light. If the EGR needs service, then I'll be looking closely at it, this is just a starting place. I knew there was a test on the vacuum side, I just did not know what it was.
From: Ray O on 29 Mar 2010 01:57 "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message news:hoomij$jl$1(a)news.eternal-september.org... > > "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message > news:hooi44$hi9$1(a)news.eternal-september.org... >> >> "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message >> news:hoo2t3$ln6$1(a)news.eternal-september.org... >>> >>> "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message >>> news:homlot$me2$1(a)news.eternal-september.org... >>>> >>>> "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message >>>> news:holl8b$k4k$1(a)news.eternal-september.org... >>>>> >>>>> "Hachiroku ????" <Trueno(a)e86.GTS> wrote in message >>>>> news:holh7v$6jn$1(a)news.eternal-september.org... >>>>>> On Sat, 27 Mar 2010 09:21:42 -0700, Jeff Strickland wrote: >>>>>> >>>>>>> I have a friend with a Camry (an '01, give or take a year), that has >>>>>>> two >>>>>>> codes stored that are both P0401. I'm not sure how the same code can >>>>>>> be >>>>>> >>>>>> >>>>>> Common Problems that Trigger the P0401 code: >>>>>> >>>>>> * Restriction in the EGR passages, usually caused by carbon >>>>>> buildup >>>>>> * Lack of proper vacuum or electrical signal to the EGR valve >>>>>> * Lack of proper EGR system feedback to the computer from the: >>>>>> Manifold Absolute Pressure Sensor (MAP) >>>>>> Differential EGR Pressure Feedback Sensor (DPFE) >>>>>> EGR Valve Position Sensor (EVP) >>>>>> EGR Temperature Sensor >>>>>> * The EGR Valve is defective >>>>>> >>>>>> Then, start here: >>>>>> >>>>>> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=EC&P=12 >>>>>> >>>>>> >>>>>> A P401 can point to other things: bad vacuum flow; this happened on >>>>>> my >>>>>> Tercel. Toyota tested the EGR (gratis) and said it was OK. I >>>>>> rectified the >>>>>> issue by putting a switch on the ECM battery wire. Hit the switch, >>>>>> clear >>>>>> the memory, drive the car two driving cycles and repeat. >>>>>> >>>>>> Finally tracked the problem to a clogged vacuum line. At first we >>>>>> thought >>>>>> it was the vacuum sensor (after the EGR) and then found the hose to >>>>>> the >>>>>> sensor was clogged. >>>>>> >>>>>> >>>>>> >>>>> >>>>> I thought the EGR gets dirty and sticks. How do you clean it? >>>>> >>>>> I'm discounting, for now, electrical or vacuum issues ONLY because if >>>>> the problem is a random occurance, this would seem to indicate a stich >>>>> valve, not missing signals or bad vac supply. Electrics or vac issues >>>>> would be less random and more constant. What I don't know at this >>>>> moment is if the problem IS random or not, and that would make a >>>>> difference, I think. But I want to start with cleaning the EGR, but I >>>>> don't know what cleaner to use, or if the valve can be cleaned in >>>>> place or has to come off to be cleaned. >>>>> >>>> >>>> You are way overthinking the problem. I would check the electrical >>>> stuff first since it is easy to check and doesn't involve removal of >>>> the EGR valve. >>>> >>>> When you diagnose a problem, check the stuff that is easy to check >>>> first, then move to the more complicated stuff, in the order of >>>> likelihood. >>>> >>>> The EGR valve and tube can become clogged with carbon. After you >>>> remove the valve, dig out what you can with an awl or screwdriver, >>>> being careful not to damage the valve seat. Some solvent may loosen >>>> some of the deposits but make sure the solvent is dry before >>>> reinstalling the valve. >>>> -- >>>> >>> >>> I thought that cleaning it WAS doing the easy stuff first. >>> >> >> The gaskets on the EGR valve should be replaced when the valve is >> removed, so just removing it means buying some parts, and messing with >> the exhaust system tends to provide ample opportunities for stripped >> fasteners so my preference is to put a meter on an electrical component >> with the component in place when possible. >> >> You can also check EGR operation with the engine idling, which is pretty >> easy. Provide vacuum directly to the EGR valve with a vacuum pump or >> bridged directly from the manifold without passing through VSV's, and if >> the EGR valve is opening, the engine should start to idle poorly and >> start to stall. If that happens, the EGR valve is not clogged. >> >> There are 2 ways to monitor EGR system operation, monitoring EGR exhaust >> gas temperature with a sensor and monitoring EGR position with a sensor. >> Rather than try to look up all the different permutations of engine and >> model year, it would be easier to just know engine and model year before >> starting research as you need that info anyway. IIRC, the 2002 is a >> different generation than the 2001. >> -- >> > > That's the kind of thing I needed to know. Thanks. > > I was thinking the problem was one those transient kinds of things, and > would not happen again very soon. If I'm wrong, then I will be looking at > this car in the not too distant future. The woman said the light had been > on for a long time -- many months. She assumed that it needed an O2 Sensor > but lacks the money to buy one or to visit a mechanic. Since the car runs > fine, she ignored the light. > > If the EGR needs service, then I'll be looking closely at it, this is just > a starting place. I knew there was a test on the vacuum side, I just did > not know what it was. > My experience with Toyota on-board diagnostics is "transient" problems that illuminate the MIL are pretty much non-existent, especially with DTC's with 2 trip detection logic. The 2-trip detection logic means that transient problems will not illuminate the MIL, and if the problem should somehow clear itself up, the MIL will go out. When a MIL is illuminated, all clearing the codes does is extend the diagnosis time because it will probably turn itself back on. -- Ray O (correct punctuation to reply)
From: Jeff Strickland on 29 Mar 2010 12:27
"Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message news:hopg75$a9r$1(a)news.eternal-september.org... > > "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message > news:hoomij$jl$1(a)news.eternal-september.org... >> >> "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message >> news:hooi44$hi9$1(a)news.eternal-september.org... >>> >>> "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message >>> news:hoo2t3$ln6$1(a)news.eternal-september.org... >>>> >>>> "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message >>>> news:homlot$me2$1(a)news.eternal-september.org... >>>>> >>>>> "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message >>>>> news:holl8b$k4k$1(a)news.eternal-september.org... >>>>>> >>>>>> "Hachiroku ????" <Trueno(a)e86.GTS> wrote in message >>>>>> news:holh7v$6jn$1(a)news.eternal-september.org... >>>>>>> On Sat, 27 Mar 2010 09:21:42 -0700, Jeff Strickland wrote: >>>>>>> >>>>>>>> I have a friend with a Camry (an '01, give or take a year), that >>>>>>>> has two >>>>>>>> codes stored that are both P0401. I'm not sure how the same code >>>>>>>> can be >>>>>>> >>>>>>> >>>>>>> Common Problems that Trigger the P0401 code: >>>>>>> >>>>>>> * Restriction in the EGR passages, usually caused by carbon >>>>>>> buildup >>>>>>> * Lack of proper vacuum or electrical signal to the EGR valve >>>>>>> * Lack of proper EGR system feedback to the computer from the: >>>>>>> Manifold Absolute Pressure Sensor (MAP) >>>>>>> Differential EGR Pressure Feedback Sensor (DPFE) >>>>>>> EGR Valve Position Sensor (EVP) >>>>>>> EGR Temperature Sensor >>>>>>> * The EGR Valve is defective >>>>>>> >>>>>>> Then, start here: >>>>>>> >>>>>>> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=EC&P=12 >>>>>>> >>>>>>> >>>>>>> A P401 can point to other things: bad vacuum flow; this happened on >>>>>>> my >>>>>>> Tercel. Toyota tested the EGR (gratis) and said it was OK. I >>>>>>> rectified the >>>>>>> issue by putting a switch on the ECM battery wire. Hit the switch, >>>>>>> clear >>>>>>> the memory, drive the car two driving cycles and repeat. >>>>>>> >>>>>>> Finally tracked the problem to a clogged vacuum line. At first we >>>>>>> thought >>>>>>> it was the vacuum sensor (after the EGR) and then found the hose to >>>>>>> the >>>>>>> sensor was clogged. >>>>>>> >>>>>>> >>>>>>> >>>>>> >>>>>> I thought the EGR gets dirty and sticks. How do you clean it? >>>>>> >>>>>> I'm discounting, for now, electrical or vacuum issues ONLY because if >>>>>> the problem is a random occurance, this would seem to indicate a >>>>>> stich valve, not missing signals or bad vac supply. Electrics or vac >>>>>> issues would be less random and more constant. What I don't know at >>>>>> this moment is if the problem IS random or not, and that would make a >>>>>> difference, I think. But I want to start with cleaning the EGR, but I >>>>>> don't know what cleaner to use, or if the valve can be cleaned in >>>>>> place or has to come off to be cleaned. >>>>>> >>>>> >>>>> You are way overthinking the problem. I would check the electrical >>>>> stuff first since it is easy to check and doesn't involve removal of >>>>> the EGR valve. >>>>> >>>>> When you diagnose a problem, check the stuff that is easy to check >>>>> first, then move to the more complicated stuff, in the order of >>>>> likelihood. >>>>> >>>>> The EGR valve and tube can become clogged with carbon. After you >>>>> remove the valve, dig out what you can with an awl or screwdriver, >>>>> being careful not to damage the valve seat. Some solvent may loosen >>>>> some of the deposits but make sure the solvent is dry before >>>>> reinstalling the valve. >>>>> -- >>>>> >>>> >>>> I thought that cleaning it WAS doing the easy stuff first. >>>> >>> >>> The gaskets on the EGR valve should be replaced when the valve is >>> removed, so just removing it means buying some parts, and messing with >>> the exhaust system tends to provide ample opportunities for stripped >>> fasteners so my preference is to put a meter on an electrical component >>> with the component in place when possible. >>> >>> You can also check EGR operation with the engine idling, which is pretty >>> easy. Provide vacuum directly to the EGR valve with a vacuum pump or >>> bridged directly from the manifold without passing through VSV's, and if >>> the EGR valve is opening, the engine should start to idle poorly and >>> start to stall. If that happens, the EGR valve is not clogged. >>> >>> There are 2 ways to monitor EGR system operation, monitoring EGR exhaust >>> gas temperature with a sensor and monitoring EGR position with a sensor. >>> Rather than try to look up all the different permutations of engine and >>> model year, it would be easier to just know engine and model year before >>> starting research as you need that info anyway. IIRC, the 2002 is a >>> different generation than the 2001. >>> -- >>> >> >> That's the kind of thing I needed to know. Thanks. >> >> I was thinking the problem was one those transient kinds of things, and >> would not happen again very soon. If I'm wrong, then I will be looking at >> this car in the not too distant future. The woman said the light had been >> on for a long time -- many months. She assumed that it needed an O2 >> Sensor but lacks the money to buy one or to visit a mechanic. Since the >> car runs fine, she ignored the light. >> >> If the EGR needs service, then I'll be looking closely at it, this is >> just a starting place. I knew there was a test on the vacuum side, I just >> did not know what it was. >> > > My experience with Toyota on-board diagnostics is "transient" problems > that illuminate the MIL are pretty much non-existent, especially with > DTC's with 2 trip detection logic. The 2-trip detection logic means that > transient problems will not illuminate the MIL, and if the problem should > somehow clear itself up, the MIL will go out. When a MIL is illuminated, > all clearing the codes does is extend the diagnosis time because it will > probably turn itself back on. > -- > There's only one code, so if there's trouble, it should be back pretty soon. How come the same code can be stored twice? I had code 01/02 and 02/02 that were both the same code. My logic says that the computer would see that it already holds the code that it's getting ready to report, so it ought not store it again. Clearly my thinking is flawed because the same code was stored twice. |