EGR sensor question.
Thread Starter
Instructor
Joined: Sep 2002
Posts: 116
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From: Boise ID
EGR sensor question.
I have noticed something strange the last couple of months and hope some people on here might have some ideas on what it could be. A couple of months ago I noticed the wire to the EGR sensor in the transfer tube was broke completely off. I found it strange that I had not noticed the check engine light coming on. Since knowing that the wire was broke I have tried to get the light to come on by meeting all the requirements like temp over 160 and speed above 45 for 15 minutes and so on. No luck, the light will come on without a problem if something else is disconnected like the TPS. I have replaced the computer about 2 years ago and checked to make sure the PROM was factory at the time. The car is not running poorly just found this strange since a lot of people have trouble keeping the light off when dealing with EGR issues.
Thanks for any help,
Ethan
Thanks for any help,
Ethan
Safety Car
Joined: Jul 2003
Posts: 3,500
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From: Saratoga Springs NY
2024 C4 of the Year Finalist - Modified
2022 C4 of the Year Finalist - Modified
Re: EGR sensor question. (ethan1321)
Apparently, some throw codes and some wont....Mine did twice, then never again...These things are not as high tech as people think.They are not programed to think as much as the newer ones, just do what they are told based on info given to them..
If your dosent throw a code-remove it and be happy!!!!!!
BTW, i wired my car so i can actually shut off the check engine light if it starts to throw codes.This way it dosent **** you off untill you fix it...Wish all cars were like this instead of a solid freaking light blinding you......
If your dosent throw a code-remove it and be happy!!!!!!
BTW, i wired my car so i can actually shut off the check engine light if it starts to throw codes.This way it dosent **** you off untill you fix it...Wish all cars were like this instead of a solid freaking light blinding you......
Le Mans Master
Joined: Jan 2003
Posts: 8,596
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From: Portland Oregon
Re: EGR sensor question. (ethan1321)
The EGR fault will set if the temp switch is not made when the EGR valve is actually commanded on. When the EGR valve is commanded on, the ECM expects to see the circuit go low at the EGR temperature switch input. This means that when the EGR valve opens to allow exhaust gases to enter the intake, the temperature rises and the bi-metallic strip "pops" and the switch closes thus completing the circuit to ground.
Now if that switch was shorted to ground all the time, the ECM should also set a code. If you were to ground the temperature switch wire as a test it should also set a code. The ECM also knows there is a problem if it sees the switch circuit grounded when the no EGR is commanded . Of course this happens only when other conditions allow for the EGR to be commanded on. Conditions such as, minimum coolant temperature, minumum TPS position, and vehicle speed and or MAP values.
[Modified by tjwong, 10:19 AM 1/1/2004]
Now if that switch was shorted to ground all the time, the ECM should also set a code. If you were to ground the temperature switch wire as a test it should also set a code. The ECM also knows there is a problem if it sees the switch circuit grounded when the no EGR is commanded . Of course this happens only when other conditions allow for the EGR to be commanded on. Conditions such as, minimum coolant temperature, minumum TPS position, and vehicle speed and or MAP values.
[Modified by tjwong, 10:19 AM 1/1/2004]
