Service Engine Soon Light

[EquatorHeat00]

Since 3 days ago my cars check engine soon light comes on for about 30 seconds then dissapears usually once maybe twice when I drive the car DAILY now. Car also shakes almost everytime I come to an idle stop while driving even when the cars warmed up. (Car still drive fine though when I smash the gas.) Can a partially bad headgasket cause this to come on which I have, or is it another problem? (I have a rattling catalytic converter as well.)

[rrz28camaro]

Have you had the code read yet? Even if it is not on, it is stored and the scanner will pick it up. Most auto part stores will scan your computer for free these days, print it out and guide you in the right direction.

[Injuneer]

You'll never know until you get it scanned. That's the whole purpose of having a light come on to tell you there's problem, and a connection to the PCM that allows you to read the codes (active and stored) to see why the light came on. Anything else is simply a guessing game.

[EquatorHeat00]

This was from FEB. 21, 2006 before my headgasket problems when I took the car in. I'll take it back in on Mon.

Computer engine analysis.

Sheet says this: Retrieve codes. Code 64. Lean exhaust bank 2. Possible causes vacuum leak, fuel pressure low, dirty fuel injectors, bad gas (not likely gas was pretty full). Clear codes. If problem recurs, further diags required.

[Injuneer]

The "lean" code sets when the long term fuel corrections are adding as much fuel as they possibly can (160 = +25% fuel) and aren't able to control what the PCM sees as a lean condition. This can be a true lean:

-vacuum leaks
-MAF sensor not producing correct readings
-low fuel pressure
-injectors not flowing at their rated capacity
-fuel contamination (has nothing to do with how "full" the tank was)

.... or it could be a "false" lean condition:

-faulty O2 sensor or sensor wiring
-exhaust leaks before the O2 sensor
-misfires

You have to narrow it down. Checking the code to insure its still the same one that was reported more than 5 weeks ago would probably be a good idea. Did the problem continue after the 2/21 diagnosis or did it go away after you refueled, and only return recently? Appears to be the latter, since you say its only been happening for 3 days.

[Joe 1320]

.... or it could be a "false" lean condition:

-faulty O2 sensor or sensor wiring
-exhaust leaks before the O2 sensor
-misfires
.

A leaking headgasket could be the culprit. Since antifreeze contains some silicones, once the stuff goes into combustion chamber and finally to the exhaust it will coat the 02 sensor, rendering it less effective.