when i pulled my tranny i found a sensor that wasnt plugged in before, so i plugged it back in and now i am getting a check engine light occasionally. It usually happens when sitting in drive or in park at idle, then when i drive off it waits a few seconds and goes away. what could this be?

 

Check the code with a paperclip. Twist it into a U and connect the upper two right terminals on your ALDL(toward the passenger side beneath your steering column) and count the flashing lights with the ignition on. Look up the code at the main page.

 

Without knowing the specific reason that your SES light is on (the code pulled), I'd hazard a guess that it's a code 24 or a code 32. We can help you a lot better once we know the exact trouble code you have. Look at the article on the main page under "technical articles".

 

As soon as it happens again i will let you guys know. thanks. --dustin

 

Grizz,

You don't have to wait for it to happen again. The ECM will store any error codes for the last 50 engine starts. As long as it hasn't been too long since the MIL lamp came on, the error code should still be recorded and will display when you scan the ECM.

Remember, install the jumper then turn on the ignition, but DON'T start the engine while the jumper is in place. You should always get a code '12' (one flash, pause, two flashes), since that means the ECM is not getting distributor reference pulses. We know it shouldn't be, since the distributor shouldn't be moving with the engine off. Each code will display three times, beginning with the '12'. The rest of the codes should follow in numerical order, then the '12' will repeat. Make a note of all codes, then turn off the ignition and remove the jumper.

 

it does the 12 and then a 4. I couldnt find the code listings on the board.

 

You must be reading it wrong. The lowest numbered code is 12 (like we said, it goes up in order).
Are you sure it wasn't 13, 22, or 31? It will pause between each digit in a code. For example, a 13 would be flash pause flash flash flash. A 22 would be flash flash pause flash flash, and so on.

Or it could be 44 and you're not counting right. It will repeat each code three times. So the code 44 would look like: F F F F (forty-) pause F F F F (four) long pause then it would repeat 44 two more times, then move on to the next code. When it's gone through all the codes, it'll flash the code 12 again.

 

it was a 44. which means oxygen sensor lean signal? How would I go about fixing this if it only happens occasionally?

 

Grizz,

If your sensor is more that 30,000 miles old, it's probably a good idea to replace it. Heated sensors last quite a bit longer, but the older design single wire sensors like ours are not that accurate after a few years of use. Failing sensors typically lose the ability to generate a good signal, and show a constant "lean" condition. This forces the ECM to "correct" the artificial lean condition by adding fuel, which costs you in fuel mileage and performance.

Other common factors that can cause or contribute to a code '44' are:

Exhaust manifold or 'Y' pipe air leakage;

Air injection system leakage, including the port/divert valve, plumbing, and fittings;

Low fuel pressure (filter, pump, or regulator);

Incorrectly adjusted TPS;

Incorrect MAP or MAF sensor signal (depending on your system);

Vacuum leaks at hoses, plenum, intake manifold, or the throttle body;

Clogging or faiiling injectors;

Excessive timing advance;

And a bucket-full of less common causes.

Test or replace the sensor first, then see if the code repeats.