02chevy silverado flashing check engine light


Asked by Jun 28, 2014 at 10:07 PM about the 2002 Chevrolet Silverado 1500 Ext Cab Short Bed 4WD

Question type: Maintenance & Repair

I just reaplaced the rear main seal
and now my check engine light is
flaking and I am hearing a strange
tapping sound any ideas?

14 Answers


The Check Engine light flashing is a pretty much universal sign that you have a misfire that is bad enough that a lot of raw, unburned fuel is being dumped in to the Catalytic Converter, to the point that it could be ruined if the problem is not taken care of very quickly. If that happens, you're looking at usually a few hundred dollars, on top of whatever the original problem is. It's also, a fire risk, as the CC already gets very hot normally, but even hotter if overloaded.

11 people found this helpful.

My truck didn't do it before we replaced the main rear seal

1 people found this helpful.

I would think you made to go have the code,s read.and yes it is probably misfire,but it also might be a bad sensor,Did you make sure you pluged all sensor in after you installed rear seal,may be just left catty oxigen sensor wire loose.

2 people found this helpful.

Does the engine seem to idle a bit rough? Another way to tell is to feel the exhuast, a constant air flow is good, but a sputtering of exhaust is a sign of a misfire. The tapping noise you have, I am not sure what that is.

3 people found this helpful.

I had my codes read at autozone today it said there is a misfire but someone on yahoo answers said it may be my catalytic converter but I didn't have any problems with that before could it b that?

2 people found this helpful.

And u said that too

1 people found this helpful.

You said it didnt start till after?

2 people found this helpful.

We checked all the plugs n yes it did not start untill after. Before it ran perfectly fine my seal was leaking so I replaced it


An engine misfire may be the fastest cause of problems for the catalytic converter. Engineers provide the check engine light with monitors to check for misfires. They program the PCM to flash the check engine light when they occur. Ignoring a flashing check engine light is an invitation to disaster. We must address a flashing check engine light immediately to avoid converter problems. The cause A misfire can destroy a catalytic converter in a matter of minutes

2 people found this helpful.

I took it to auto zone the codes read : a cylinder misfire detected-random cylinders Explanation: the power train control monitors the crankshaft speed and and detects a misfire condition. Probable cause: Ignition system Fault- spark plugs Ignition wires Vacuum leak Injector fault High or low fuel pressure

1 people found this helpful.

I'd go with a possible vacuum leak. You removed a lot to change the rear main seal and may of not connected everything up tight. Sometime moving one item will start a slight break in another seal. Have the fuel system checked for leaks. Have the ignition system checked for lose wires or bad sensors or computer module. Since you state the misfire is random, it is not at just one cylinder, but in you command module that controls the ignition. or plug firing. The knock. Do you know were it is coming from? Could it be the misfires or the crank hitting something not p;ut in correct when replacing the seal? Use a stethoscope to find the knock. It very well could be the misfiring causing the knock. Believe the codes.

1 people found this helpful.

Mine has flashed for 6 years, don't worry about it.


I just purchased a 02 silverado 1500hd with a 6litre.same issue!flashing check engine light. Rough idle.any ideas??new manifolds..plugs and wires.was told that the cats may be plugged up.gutted them and it still flashing.help!!lol

1 people found this helpful.

Your cats send messages to the computer that runs the ignition timing and fuel settings. With plugged or gutted cats, the computer is getting bad messages. Replacing the manifolds means there was either major problems, or customized work was done to the engine. Have you tried to resink the computer to the new equipment? Is everything hooked up correctly? Vacuum leaks can rase havoc, and wrong sensors also. What else was done to modify the engine? If you just bought the truck, was it an "as is" purchase, or from a dealer that you can take it back to to find the issue and repair it?

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