Camry EGR Valve, Code P0401
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From: Hachiroku ハチロク on 27 Mar 2010 14:02 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.
From: Jeff Strickland on 27 Mar 2010 15:10 "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.
From: Hachiroku ハチロク on 27 Mar 2010 16:45 On Sat, 27 Mar 2010 12:10:56 -0700, Jeff Strickland wrote: > > "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've exhausted (no pun intended) the scope of my knowledge. I think you just unbolt the thing and undo the vacuum lines. It can be tesetd by blowing into it and doing the vacuum test. The failure rate on these is pretty low, I would try other things first. Of course, now that I have said that, it will be a bad EGR.
From: Michael on 27 Mar 2010 18:55 On Mar 27, 7:10 pm, "Jeff Strickland" <crwlrj...(a)yahoo.com> wrote: > "Hachiroku ????" <Tru...(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.... > > > 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 have to remove the EGR valve and pipe, and clean the pipe (and valve) with throttle plate cleaner, brake pad cleaner or some similar solvent. It was easier for me to remove the throttle body, then I saw the large nut connecting it to the engine. That nut was easier to remove than the one straight down from the EGR valve. Of course, after I did this, it wasn't the EGR valve (or dirty throttle body) after all... later traced my stalling problem (no engine code) to a bad ECT sensor on my '96. Michael
From: Ray O on 28 Mar 2010 00:25
"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. -- Ray O (correct punctuation to reply) |