QuestionMy girlfriend owns a '91 Galant. Due to stalling
and being unable to start, the fuel injection
relay and main computer were replaced by a
mechanic. The car runs again (well) but now the
check engine light is on. The mechanic claims
that the barometric pressure/mass air flow sensor
needs to be replaced. (According to the computer code) The engine light was not
on before this repair. The vehicle runs excellent
and passes emissions. Any ideas?
AnswerMark,
If you have an AutoZone in your area, you can bring your car to them and ask them to scan your car's computer for a second opinion. They offer this for free. If your problem is the barometric pressure sensor/mass air sensor, it may just be a loose connection harness. The mass air sensor is pretty expensive, so only replace that if you really having a problem. You may even just need to replace your air filter. Sometimes an excessively dirty air filter will cause the check engine light to come on.
You may even have luck by simply resetting your car's computer. This is done easy enough by disconnecting the negative battery cable from the battery for about 30 seconds. Then reconnect the cable, and your check engine light should be reset. If you start your car and the check engine light comes back on and stays on, then it's still detecting a problem. You can check all the harnesses connected to your air filter housing, and you can replace you air filter if you wish. It should be changed every couple years or around 20,000 miles. But if your light stays on, but it's not causing any problems (and your safety and emmisions inspectors don't care), you should be fine with it on. There's a possibility that the new computer that was installed was a refurbished computer from a slightly different model of Galant and it's getting a little confused by your mass air sensor. Not a big problem if your car is running fine, though.
Good luck!
