Sensor, Code Clearing, Service Engine Soon Question

engines
lights
chevrolet
lumina
sensors

#1

About a month ago, my 96 Chevy Lumina suddenly and briefly had fluctuating RPMs before stalling. I restarted it, and it ran fine, with the “Service Engine Soon” light on. Later that day, the light went out. Two days later, it did a similar thing, but did not quit running. Again, the light came on and then went out. Later that week, I took the car in to a shop. Even though the light was not on at the time, a scan found problems with a couple of sensors-The MAP (manifold absolute pressure) and the MAF (mass air flow) sensors. Based on the mechanic’s recommendation, we had the MAP changed and he cleaned up the MAF sensor, hoping that would do the trick. Of course, we did not even get home before the light came back on the dash. Now knowing what sensor should be changed, and considering the expense of having the MAF changed by someone else, I got a new MAF sensor and changed it myself. It was a pretty easy job. The mechanic had told me that after changing it, the car would realize it had a new sensor and, after a while, the Service Engine light would go out. Well, it’s been over 3 weeks and about 1500 miles since I changed that sensor, and the light remains on. The engine runs well, but I’d like the light to be out, so that when something else actually goes wrong, I’ll know it. Any recommendations on getting the light out cleaply? I hate to bring it in to have the codes cleared as it is probably not cheap. At this point, I’m sure it’s not going to just go out on its own. Thanks!


#2

First, do keep in mind that there are no codes that tell you to change sensors. The sensors might actually be doing their jobs by sensing problems & reporting it to the computer.

In this case, if your symptoms have disappeared then one or both of those sensors MAY have needed to be changed. You should clear the codes to find out since they will come back if there are still issues.

You can disconnect the battery for 30 secs or so, though some people recommend against that. You can search these boards for threads about it.

Or go to a large chain auto parts store (e.g. Autozone, Advance). They will scan it for free so that you can see what codes remain in there, and then you can ask them to clear the codes. This will reset the light and it will then come back on if you have the same (or some other) problem.

If you do have it scanned write down the exact codes that come up - as in P1234 and keep those handy. If your light comes back & you want help w/ it people will need an exact code - rather than something like “a problem with X sensor” which is only marginally helpful.