Dtc P0402

[hdygma]

I recently ran into this trouble code and managed to troubleshoot it through to resolution. I thought I'd post since mine was slightly different than others.

Symptoms:

Hesitation at slow speeds (between 10 and 30 mph). This was the first symptom. From time to time I would experience severe hesitation on hard acceleration from a stop (for example when merging with traffic on the highway). The car would buck and spit and the Trac Control light would light up and go out.

Eventually the CEL and Trac Control light lit at the same time and stayed on.

At all other speeds and conditions the car ran satisfactorily.

Diagnostics:

I bought a code reader and read a DTC of P0402 (Excessive EGR)

Troubleshooting:

I read the FSM on EGR. It pointed to the EGR valve itself, the EGR position sensor, and the VSV as logical first places to start.

I did not believe the EGR was truly allowing excessive flow since the car idled fine. Excessive flow would create a rough idle or inability to hold an idle. The car has 140K miles on it and I figured it couldn’t hurt to pull the EGR to clean it regardless. I checked operation for smoothness and ability of the valve to seat tightly and did not spot any issues. I cleaned it with throttle body cleaner as best I could and reinstalled it.

Next I checked the ERG Position sensor according to the manual. It did not give the correct resistance readings at the sensor. The harness end was within the voltage range.

I did not believe the VSV was faulty since it would contribute to poor idle issue mentioned above if it was passing too much vacuum. If it was passing too little vacuum, I’d get a different code altogether. I followed the troubleshooting steps outlined in the FSM. All voltage, resistance, and vacuum flows were according to the ranges and specifications in the manual.

Fix:

I replaced the EGR Position Sensor and cleared the DTC memory.

Notes:

The car has been driven about 2 weeks and about 600 miles. No CEL light, no Trac Control light, and no hesitation. The code reader I have can monitor codes as they are written to memory even before they trigger the CEL light. This code requires a 2 trip detection to trigger the CEL. So far the memory indicates no trouble codes detected, not even a single detection.

I was unable to find an EGR Position Sensor on line or at any local parts houses. Most would tell me it they didn’t stock it or it was a dealer part. I wound up ordering it from Toyota for $49.00. Prices ranged from $42 to $64. Nobody stocked the part (including Lexus and Toyota). Turnaround was 2 days.

The part number has changed from 89455-33020 to 89455-33010. Don’t be alarmed if it does not look exactly like the original part. The newer one is smaller and has a different profile.

If anyone can recommend a reputable parts website I would be grateful. It was a pain trying to locate this part on line.

If anyone has any questions feel free to send me an email.

[98OysterES300]

I recently ran into this trouble code and managed to troubleshoot it through to resolution. I thought I'd post since mine was slightly different than others.

Symptoms:

Hesitation at slow speeds (between 10 and 30 mph). This was the first symptom. From time to time I would experience severe hesitation on hard acceleration from a stop (for example when merging with traffic on the highway). The car would buck and spit and the Trac Control light would light up and go out.

Eventually the CEL and Trac Control light lit at the same time and stayed on.

At all other speeds and conditions the car ran satisfactorily.

Diagnostics:

I bought a code reader and read a DTC of P0402 (Excessive EGR)

Troubleshooting:

I read the FSM on EGR. It pointed to the EGR valve itself, the EGR position sensor, and the VSV as logical first places to start.

I did not believe the EGR was truly allowing excessive flow since the car idled fine. Excessive flow would create a rough idle or inability to hold an idle. The car has 140K miles on it and I figured it couldn’t hurt to pull the EGR to clean it regardless. I checked operation for smoothness and ability of the valve to seat tightly and did not spot any issues. I cleaned it with throttle body cleaner as best I could and reinstalled it.

Next I checked the ERG Position sensor according to the manual. It did not give the correct resistance readings at the sensor. The harness end was within the voltage range.

I did not believe the VSV was faulty since it would contribute to poor idle issue mentioned above if it was passing too much vacuum. If it was passing too little vacuum, I’d get a different code altogether. I followed the troubleshooting steps outlined in the FSM. All voltage, resistance, and vacuum flows were according to the ranges and specifications in the manual.

Fix:

I replaced the EGR Position Sensor and cleared the DTC memory.

Notes:

The car has been driven about 2 weeks and about 600 miles. No CEL light, no Trac Control light, and no hesitation. The code reader I have can monitor codes as they are written to memory even before they trigger the CEL light. This code requires a 2 trip detection to trigger the CEL. So far the memory indicates no trouble codes detected, not even a single detection.

I was unable to find an EGR Position Sensor on line or at any local parts houses. Most would tell me it they didn’t stock it or it was a dealer part. I wound up ordering it from Toyota for $49.00. Prices ranged from $42 to $64. Nobody stocked the part (including Lexus and Toyota). Turnaround was 2 days.

The part number has changed from 89455-33020 to 89455-33010. Don’t be alarmed if it does not look exactly like the original part. The newer one is smaller and has a different profile.

If anyone can recommend a reputable parts website I would be grateful. It was a pain trying to locate this part on line.

If anyone has any questions feel free to send me an email.

OEM Lexus Parts --- 15% over cost at Pembroke Pines Lexus or Pembroke Pines, Florida

http://www.trademotion.com/partlocator/ind...m?siteid=214082

I've ordered here before & got the best prices & pretty quick turnaround time as well!

[hdygma]

I recently ran into this trouble code and managed to troubleshoot it through to resolution. I thought I'd post since mine was slightly different than others.

Symptoms:

Hesitation at slow speeds (between 10 and 30 mph). This was the first symptom. From time to time I would experience severe hesitation on hard acceleration from a stop (for example when merging with traffic on the highway). The car would buck and spit and the Trac Control light would light up and go out.

Eventually the CEL and Trac Control light lit at the same time and stayed on.

At all other speeds and conditions the car ran satisfactorily.

Diagnostics:

I bought a code reader and read a DTC of P0402 (Excessive EGR)

Troubleshooting:

I read the FSM on EGR. It pointed to the EGR valve itself, the EGR position sensor, and the VSV as logical first places to start.

I did not believe the EGR was truly allowing excessive flow since the car idled fine. Excessive flow would create a rough idle or inability to hold an idle. The car has 140K miles on it and I figured it couldn’t hurt to pull the EGR to clean it regardless. I checked operation for smoothness and ability of the valve to seat tightly and did not spot any issues. I cleaned it with throttle body cleaner as best I could and reinstalled it.

Next I checked the ERG Position sensor according to the manual. It did not give the correct resistance readings at the sensor. The harness end was within the voltage range.

I did not believe the VSV was faulty since it would contribute to poor idle issue mentioned above if it was passing too much vacuum. If it was passing too little vacuum, I’d get a different code altogether. I followed the troubleshooting steps outlined in the FSM. All voltage, resistance, and vacuum flows were according to the ranges and specifications in the manual.

Fix:

I replaced the EGR Position Sensor and cleared the DTC memory.

Notes:

The car has been driven about 2 weeks and about 600 miles. No CEL light, no Trac Control light, and no hesitation. The code reader I have can monitor codes as they are written to memory even before they trigger the CEL light. This code requires a 2 trip detection to trigger the CEL. So far the memory indicates no trouble codes detected, not even a single detection.

I was unable to find an EGR Position Sensor on line or at any local parts houses. Most would tell me it they didn’t stock it or it was a dealer part. I wound up ordering it from Toyota for $49.00. Prices ranged from $42 to $64. Nobody stocked the part (including Lexus and Toyota). Turnaround was 2 days.

The part number has changed from 89455-33020 to 89455-33010. Don’t be alarmed if it does not look exactly like the original part. The newer one is smaller and has a different profile.

If anyone can recommend a reputable parts website I would be grateful. It was a pain trying to locate this part on line.

If anyone has any questions feel free to send me an email.

OEM Lexus Parts --- 15% over cost at Pembroke Pines Lexus or Pembroke Pines, Florida

http://www.trademotion.com/partlocator/ind...m?siteid=214082

I've ordered here before & got the best prices & pretty quick turnaround time as well!

Quick note: Car has 150K miles and is still running great.

Thanks 98OysterES300 for the parts tip.

[foxt]

Hi,

I have the exact same problem as you had. And the trouble codes are confirming that its the EGR valve position sensor. I noticed that my sensor is the triangle shape that bolts down to the valve, yet in the picture of the part that I think you referenced, the replacement part doesn't appear to have that flange but rather crews into the valve? Is that right? I can find the exact replacement (the part with the flange and the three bolt holes) via Autozone, but they want $98.99 for it. Looks like that flangeless part is less than half the cost. Can you confirm that you went with the flangeless model and it somehow mounted into the hole in the EGR valve?

Thanks,

Tom

[philipwk]

Where is the ERG Position sensor located?

Got a photo?

pk

[camlex]

I did replace in my 97 ES300 for $35 from Orailly. Part# was EGR500

Here is the location which has electrical connector.

[philipwk]

Hay thanks for the quick reply...

However on my 1995 ES300 I do not have that electrical unit on top

of my EGR valve...see photo.

I am STILL trying to find out where the ERG Position sensor located.

If there is one on a 1995!

Any help would be great.

philipwk

[George_Jetson]

95 does not have a egr position valve. The original post is for 97, which does have a position sensor.

[philipwk]

Yea,

At this point the question is, is there any other method Lexus uses to measure the EGR pressure

and if there is should i test IT, or just change the EGR and hope for the best?

pk

[George_Jetson]

95 does not measure egr pressure, Although I will commend you for taking the initive to research the problem instead of jumping right in with the questions, the approach to troubleshoot this must be different.

What the issue you are having is that although the code is the same, the method that they detect the condition is totally different. This year uses a temp sensitive resistor to measure the presence of EGR, with no egr flowing it expects to see low temps. The code is for excessive flow, so it thinks there is egr when it is not called for. If you have a hand held vac pump, you could apply vac to the egr and see if it moves freely, and then returns to the closed position when vac is removed. Next start the engine and let it idle ( I assume that idle quality is good ). With the engine at idle, apply vac to the egr valve. It should stumble and run VERY rough, if not die alltogether. With these tests you have elimated the egr valve (or condemed it). If you do not have a hand held pump, I would recomend buying one, it will come in very useful for many different things. Harbor Freight sells a cheapie that will work ok for a average person. It run around $10

The next step I would recomend checking the temp sensor Measure the resistance, I believe that it should be around 2.5 k ohms when cold.

Try these things, and then let us know what you have found, chances are you will have found the problem with these tests, if not, I can tell you how to the the other components in the system.

[philipwk]

Hay this is great stuff George thanks.

As a matter of fact I HAVE one of those hand held pump/vac I bought from Harbor F and have not used it for months.

It's late here now and won't have time to perform the tests, but I will tomorrow and will keep in touch.

Just need to locate the resister, I also have a Volt/Ohm meter no problem.

pk

[philipwk]

WOW, it hard to work on this car when the wife works so long of hours.

SO, I pulled a vacuum on the hose that goes to the top of the EGR Valve and sure enough the engine idles very rough and almost dies

then goes back to good idle when I let loose the vacuum. EGR must be ok.

I then red the voltage accross the EGR Gas Temperature sensor and at idle it is about 3.9 volts then as I increase the RPM it drops

below 2 volts in about 30 seconds. It may be ok. I also read NO ohms accross it. Being a sensor there maybe should not be.

I then check the Vacuume switching Valve (see photo) I get 1k ohms accross the leads on way then switch the leads and I get an open curcuit.

I can not draw vacuum on either hose fittings weather I put voltage on it or not, I get air through it at both fittings, both ways.

This may be the problem.

Your turn!!.....just kidding.

phil

[George_Jetson]

SO, I pulled a vacuum on the hose that goes to the top of the EGR Valve and sure enough the engine idles very rough and almost dies

then goes back to good idle when I let loose the vacuum. EGR must be ok.

This indicates that the erg valve is good.

I then red the voltage accross the EGR Gas Temperature sensor and at idle it is about 3.9 volts then as I increase the RPM it drops

below 2 volts in about 30 seconds. It may be ok. I also read NO ohms accross it. Being a sensor there maybe should not be.

This appears to be a contradiction, the changing voltage does not agree with NO ohms. I believe that it should read app 2.5 k ohms when cold, and less when hot. Does your DVM have a auto range, or manual range? My guess is that it was on the wrong range.

I then check the Vacuume switching Valve (see photo) I get 1k ohms accross the leads on way then switch the leads and I get an open curcuit.

I can not draw vacuum on either hose fittings weather I put voltage on it or not, I get air through it at both fittings, both ways.

I will need to look up the actual vac ports on the valve, this may be the problem. I am at work right now and do not have access to my manuals

This may be the problem.

Your turn!!.....just kidding.

phil

[George_Jetson]

Ok Alldata indicates that the coil should read about 33 to 39 ohms, assuming they are right, you have a problem.

The black thing on the right hand side of the valve is a filter. According to alldata with no power applied to the valve you should be able to blow air from the center port (the one pointing up in you picture) to the port and the left hand side. Then if you apply 12 volts across the terminals, you should be able to blow air from the center port, to the filter on the right hand side.

There are two things that concern me.

1) you read the wrong resistance on the egr temp sensor, this is confusing since the voltage readings that you are getting are app what I would expect. So with this in mind, I would note this, but take no action at this point. Focus your attention on the valve.

2) you are reading a much higher resistance on the valve than what the spec calls out. If you have access to a air compressor with a regulator you can set the reg to 10 to 15 psi. Rig up fittings so that you can apply the pressure to the center fitting and see what happens. You want to be able to apply 12 volts and see if the valve switches. If it does switch, see if you can get it to reliably while switching it fairly rapidly.

I recomend testing the valve, with a compressor, my guess is that you will probably find the problem here. I work with this type of computer controlled valves every day, it is very possible that the valve is sticking and causing this problem. From the schematics, it appears that it is used in a pulse width modulated circuit and sticking would explain the problems you are having. The fact that some of the other data is contadicting is making this a little more difficult, but the test on the valve will tell us a lot.

[philipwk]

Hi, George,

I again verified when blowing on the center port, the only place the air comes out is the other left hand

port, appling 12Volts made no difference at all. In no case could I get air to come out the filter.

I'll perform this test again tonight when she gets home and I have a regulator in my air line.

This resistor "egr temp sensor" you are calling it, the only thing I found that could be that is what they

are calling "EGR Gas Temp Sensor" (see photo) I have not found a resistor (we may be talking about

the same thing). I again measured this sensor and I get NO resistance, I checked the DVM at 2k, 20k 100k

and still it shows open.

[George_Jetson]

Ok, since the resistance of the valve is too high, and it is not switching I would say replace the valve. I would suggest that when you pick up the valve, that you also see if they have the egr sensor. If you bring your meter with you, you can compare the readings with what the sensor on your car is reading. At this point I would NOT purchase a sensor. The fact that the valve is not switching is enough to explain why you are getting the code.

[philipwk]

Ok I'll get one tomorrow, Appeaciate....I'l be in touch to let you know what happends.

pk

[94LexusES30054]

yes my 94 Lexus has been doing the same thjg but my. code is p1600 ecm batt I can't figure out what the issue is to fix it so the check engine will go off so I Can register it its been three moths and no sucses any one got any suggestions what ecm batt could. be or how to fix sed issue