2003 Chevrolet Monte Carlo Engine

  • 3.8L
  • V6
  • FWD
  • 135,000 MILES
I was driving home from work and ended up going through a pretty good size puddle. A few hours later when I was going to work again, I started my car only this time the check engine light was blinking and the car was chugging/shacking. Since than the light has been on completely, no blinking, and still the same way. I read online it may be cause from my engine suckling in water and everything getting wet but it ran fine all day today and I've never once had a problem with it. That car has been sitting since 11:30pm and I'm off at 6am. Will it be ok to drive home? I'm really concern.
Do you
have the same problem?
Monday, April 20th, 2015 AT 12:03 AM

1 Reply

The vibrating engine is due to a misfire which can be explained by water getting on the spark plug wires or ignition coil(s). A spark-related misfire will send unburned fuel into the exhaust system where it can overheat and damage the expensive catalytic converter. That is what the Engine Computer sees and is what the flashing Check Engine light refers to. You're supposed to stop the engine right away to avoid damaging the catalytic converter.

Even though the problem may have cleared up on its own, since a misfire is a pretty serious event in terms of emissions, the Check Engine light will be "latched" on until the fault code is read and erased. When minor problems go away on their own, if the Check Engine light was on, it will turn off by itself.

It is very possible there is no longer a problem but you won't know for sure until the fault codes are read. The people at many auto parts stores will read them for you for free. Be sure to write down the exact fault code numbers, not just the generic description. Once the code numbers are recorded, the codes can be erased. If there is still a problem, it will be detected by the computer and the appropriate code(s) will set again.

Even though the engine may seem to be running fine now, what is more important is since the Check Engine light is on now, anything the computer uses for comparisons when it's running other tests can't be relied on to give accurate results, so some self-tests will be suspended. That means there can be some other problem that doesn't get detected. In this case, once the current codes are erased, those tests will resume, and that's when any new problems may turn on the Check Engine light again. At that point, read the codes again to see if new ones are set or if it's the same codes that were just erased.
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Monday, April 20th, 2015 AT 12:32 AM

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