Solenoid repair


My '96 Jetta just got a Reject sticker for emissions failure. The inspector said it could be the solenoid. Can anyone tell me what is involved with fixing that? I don’t want to spend a couple of limbs on a 12-year-old car, but I’m kind of hosed because I’m now driving around with a Rejection sticker. Thanks to anyone who can fill me in.


I suspect they were talking about the evaporative emissions purge solenoid. While your car is sitting idle, the evaporative fumes from your gas tank are captured and stored. When you start the engine, the purge process occurs and the fumes are drawn into the engine to be burned. Usually, there are solenoid(s) in this circuit to control the flow of gases. However, this is a wild guess and guessing can be quite expensive. Much better to have a proper diagnosis on the problem and fix only what needs fixing…


Thanks Twin Turbo. Your guess is a more articulate version of a friend’s assessment, and this is helpful to me. Thanks for taking the time to respond. Bill


No problem, glad I could be of some help. Normally, the check engine light will come on in response to a problem like this. Is your’s on or has it come on and gone out? Did the inspector list any diagnostic trouble codes that led them to fail your car? While the codes are not always definitive on the cause of the problem, they are very helpful in diagnosing the failure.


Another thing you should check is the EGR valve. They can get carbon buildup and cause a emissions test failure. Cleaning them up with solvent usually makes them work properly again.

In order to figure out what should be checked it would be helpful to know what the test results were.


Actually, the check engine light has been coming on and and off sporadically over the last couple of years. My regular mechanic has addressed the issue, supposedly, several times, and then the light comes back on a few weeks later. He’s not an inspection station, and the emission test is not performed every year at the station where I do get the inspection, so I haven’t had any problem 'til now. There is a printout with diagnostic code on it, so I’m assuming that this mechanic (the one who did the inspection, not my regular guy) has a starting point. I’m wondering if the actual issue was ever really addressed. Can the engine light be re-set without addressing the issue that activated it?


The ECU can be reset and clear the codes but it will also clear the monitors and a minimum of these need to be set when the test is done. It takes a fair amount of driving to set the monitors. If there isn’t enough monitors set when IM testing is started the testing stops there.