"Service Engine" Light On (Pontiac Sunfire)

There are too many to list. Around 3,400 or so.

Another

Get it scanned and report back with the error code. Places like Advance Autoparts and PebBoys will often due it for no charge.

matt1986 wrote:

Funny, I went to this site, because my Service Engine light is also always on. I have also had problems with the Coolant, Gas, and several other idiot lights coming on randomly or staying on.

Someone on the site mentioned rapping the control box (I saw two of them up top, near the firewall) with the end of a screwdriver. I did, and guess what: all the red idiot lights went off...for good it seems ( I mean, hopefully they would come on normally if there's a real problem).

I also recently had my "manifold sensor" replaced to stop a problem with the engine conking out on idle at a stop sign. I'm going back to my mechanic, because it didn't fix the problem at all!

But here's what happens, when it cold starts, it doesn't have the problem because it sets a high idle. Then, after driving, when it warms up, it conks out. When I come to a stop, the idle steps down, and then it kind of wheezes ( I can see the dashboard lights fade and come back, as if the car were trying hard to /breathe/ ), then it dies.

Occasionally it seems to do a reset, where it won't start for a few seconds ( like a fuel line cutoff switch or something ).

One thing I did do is move the cable around that goes to the two circuit/sensor boxes mentioned above -- it seemed to affect the idle. One cable runs right near the alternator, and I'm wondering if it doesn't have anything to do with heat/interference affecting the electronics.

Heat would be a hard call, because it seems that when the car runs warmer, like when I drive it slowly around the parking lot, and it goes up to 220, then it doesn't have the prolbme. When I highway drive, it looks like it goes as low as 160, and that's when the problems start...but that's only after driving a while.

When it's cold starting and heading up towards 160, then its still got the high idle.

Still, I'm thinking its some combination it setting too low an idle for running at 160, or the themostat control setting to a low a rest temperature in general.

FBR wrote:

There is no such thing as a control box or manifold sensor. It would be helpful to you and to us here if you could find out what the technical names of those parts are.

Or wait...it's probably this:

The Manifold Absolute Pressure sensor measures changes in the intake manifold pressure resulting from engine load and speed changes. The computer sends a 5-volt reference signal to the MAP sensor. As pressure changes in the intake manifold occur, the electrical resistance of the MAP sensor also changes. By monitoring the sensor output voltage, the computer can determine the manifold absolute pressure. The higher the MAP voltage output the lower the engine vacuum, which requires more fuel. The lower the MAP voltage output the higher the engine vacuum, which requires less fuel. Under certain conditions, the MAP sensor is also used to measure barometric pressure. This allows the computer to automatically adjust for different altitudes. The computer uses the MAP sensor to control fuel delivery and ignition timing."