Need Help On OBDII Code P0402

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Old 03-14-10, 02:51 PM
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Need Help On OBDII Code P0402

1995 Toyota Camry AT V6 3.0L Wagon, 98,138 miles. Got check engine light on and had OBDII scanner extracts code 0402. Need help on what I should check with this error code and how? Thanks!
 
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Old 03-14-10, 03:08 PM
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It appears to be:

0402 Exhaust Gas Recirculation Flow Excessive Detected

Check to see if your EGR valve is carboned up and stuck open.

Here are the OBDII difinitions:

http://www.tazcobra.com/obd2_dtc.pdf
 
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Old 03-14-10, 06:16 PM
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Do I have to take the entire piece off to check? Visually check, functional check (how?), or both?
 
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Old 03-14-10, 06:30 PM
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They make all these things differently. I don't know about your specific vehicle...

I would remove it and look at it. See if I could clean it. Some would be easy to see inside and clean. Others I imagine they would design so you can't see anything.

Be careful to not get any cleaning fluid on any electrical portions of the valve if it works that way. Might hold the electrical portion up so fluid does not drip down on it.

This is a common problem, so tons of information on the internet. Here is a search...
Google
 
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Old 03-14-10, 06:56 PM
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Other than the EGR valve itself sticking one way or the other you can have a bad Vacuum Switching Valve or a burned out diaphragm on the modulator. The latter likes to happen frequently.

Autozone may have the testing procedures for that car on those two components. It's about the same setup for all the toyota engines of that year.
 
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Old 03-15-10, 12:06 PM
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Thanks for all of your replied! I will check them out on this coming weekend and post it back.
 
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Old 03-23-10, 11:51 AM
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Did a quick check of Vacuum Regulator Valve by taking it off and inspect a week ago. Didn't seem to have any deposit and used paper clip to check all tub path ways. Put it back and reset check engine light. Drove for a week since then and the light didn't come on. Looks like it was fixed. Thanks all!
 
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Old 04-06-10, 04:22 PM
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The problem came back several times. I cleaned EGR valve and path ways use air blower. I don't know what else I can check. How can I check a EGR valve is good or bad? Any help would appreciated!
 
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Old 04-06-10, 04:43 PM
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I imagine that as with all things automotive, EGR valves would be different in various brands/models of vehicles.

So there probably is no set way to test these.

To know for sure how to test your specific EGR valve, you would need the factory service manual and that would say how to test this. And that is around $150 for the set.

And if it was electric and had a pulsed stepper motor, then you would need a special electronic tool to test it.

Or determine the timing of the electrical pulses, an oscilloscope.

Or to test with vacuum, a vacuum pump.

Etc.

Me thinks it might be cheaper to just get a new one?

Here is a general blurb on all valves which might help...
EGR Systems: Operation and Diagnosis
 
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Old 04-24-10, 12:09 PM
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Follow Haynes repair manual and found the defect VSV (Vacuum Switching Valve). There are three VSV in this car and they all look different. The repair manual says it is between 33 to 39 ohms. The defect is in the center and has no ohms reading. Bought it, changed it, and reset check engine light. after a few days of driving, the check engine light comes on again, but with different code. It is P0401 this time and it could be the EGR gas temperature sensor according to manual. I remembered I took it off and saw black carbon deposit almost cover the entire brass area. I used wire brush to clean it. Could this cleanning process damage EGR gas temperature sensor? Any idea to fix P0401 code?
 
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Old 04-24-10, 01:21 PM
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Never mind, found the EGR temperature sensor plug didn't connect from last cleaning.
 
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