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Check Engine light

1656 messages,  Last post on Nov 10, 2009 at 6:37 PM

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What is this discussion about? Fuel System, Electrical, Engine

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#1627 of 1656 Re: MIL following exhaust repair?? [wb2eqe] by diy_dad Feb 18, 2009 (12:58 pm)
Replying to: wb2eqe (Aug 04, 2008 3:11 pm) In california its really tough to pass a smog test I had a oxygen sensor replaced and the check engine light came back on, Complained to the shop that did the work and they had no idea why the light returned finally found the answer on this site http://repairpal.com/check-engine-light "On vehicles 1996 and newer, using an inexpensive "universal" oxygen sensor will cause problems with the emissions system." How frustrating is that these shops are using universal oxygen sensors and charging dealer prices for the part, They finally put the dealer part in and the light went off and passed smog only took three weeks and I had to show them this website before they would put in the correct part.
#1628 of 1656 Re: Global Warming is a myth and [Mr_Shiftright] by isellhondas Mar 05, 2009 (2:11 pm)
Replying to: Mr_Shiftright (Dec 20, 2008 12:00 pm) We love it when people are trading in cars with a CEL on.   They will ALWAYS say..." It's probably a loose wire or something minor"   Yeah, right!   A store HAS to assume the worst because that's usually what it is. It can be a bad transmission, bad computer or a bad converter.   We will appraise the car accordingly and so will any smart store.   Had a trade in last summer with an air bag light on. A Volvo naturally. The Volvo Dealer charged us 1200.00 to fix whatever it was. It wa NOT a loose wire!
#1630 of 1656 Re: Cnlight is looking for commission agents [lamjames] by obyone Mar 13, 2009 (8:26 pm)
Guangdong P.R.C   Hmm. Chinese spam. Sweet sour. Replies to this message: Mr_Shiftright (Mar 14, 2009 9:28 am)
#1631 of 1656 Re: Cnlight is looking for commission agents [obyone] by Mr_Shiftright HOST Mar 14, 2009 (9:28 am)
Replying to: obyone (Mar 13, 2009 8:26 pm) spam now in the can.
#1632 of 1656 check engine light concern by jeffreyb4 Apr 08, 2009 (10:51 pm)
My check engine light was on, code checked & cleared by a local mechanic. The code indicated PCM problem. The light came back on so I took it to a dealer to have PCM replaced (under warranty). The dealer checked & confirmed the PCM code and agreed to replace it at no cost. However, while at the shop, another code appeared that was not there before. This code indicated knock sensor and the dealer said this would cost $340. My question is, why did this code suddenly appear at the dealer? Is there a way to program this code to show up falsely? I think they may have done this on purpose and there was actually no problem with the knock sensor until they did something to make it show up. Is this possible? Thank you for any advice. Trying not to get the run around by an unscrupulous dealer. Replies to this message: kiawah (Apr 09, 2009 3:22 am) euphonium (Apr 09, 2009 2:42 pm)
#1633 of 1656 Re: check engine light concern [jeffreyb4] by kiawah Apr 09, 2009 (3:22 am)
Replying to: jeffreyb4 (Apr 08, 2009 10:51 pm) Nope, you worry too much.   The engine computer is monitoring all of the sensors in the car, and using them to adjust other things and keep the engine running at optimal condition.   Some sensors are always sending back a signal, and if you don't get a signal, you know something is most likely bad. For instance, each wheel has sensor, and when the vehicle is moving forward straight the computer would see 4 signals, all at the same pulse rate. If you only got 3, then it's relatively easy to figure out that either one wheel is locked up and skidding, or the sensor is bad.   Some sensors, the computer has to deduce there are problems, by the process of elimination. Or, it can never know exactly and call out multiple possibilities. The knock sensor is a sensor where you don't normally get a signal, except when engine is heavily overloaded and starts to ping/detonate early. If the computer never receives a signal, the computer thinks that the engine is running okay....yet the engine could be severly overloaded and spark timings and mixture should be adjusted.   The analogy I'd give you is a fire alarm. You don't normally hear a fire alarm in your building, and because of that you think it's a safe working environment. However, if you walk out of the office, and it feels warmer than usual, you may think the air conditioner is not working correctly. A little bit later, if you also see and smell smoke, then you now suspect there is a fire, and then realize that the fire/smoke sensor must be defective because it never triggered and reported a problem.   So sometimes it is relatively quick and straight forward to figure out EXACTLY what is wrong. Most of the time, the engine can very quickly deduce there's only a couple of potential causes to the problem. Other times it takes more analysis or longer time to monitor multiple situations before it's able to figure out the cause. Sometimes the computer will never figure out the right cause, and it takes a humanoid to figure it out, by process of elimination or deduction.
#1634 of 1656 Re: check engine light concern [jeffreyb4] by euphonium Apr 09, 2009 (2:42 pm)
Replying to: jeffreyb4 (Apr 08, 2009 10:51 pm) If the knock sensor is, like the PCM, germain to the Emission System shouldn't that be covered under warranty as well?
#1635 of 1656 starting problem by tjacks1 Jun 01, 2009 (12:27 pm)
when i turn the key nothing happens i get the dummy lights the battery is good i can jump the starter with a screwdriver and the car turns over but still wont start any sugestions on what might be the problem Replies to this message: kiawah (Jun 01, 2009 1:04 pm)

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