Check Engine light

[CMoore]

I need help. I have a '99 Explorer, and have had many problems lately. Recently the thermostat was changed by my father in law and it worked fine for a few days, until my husband saw smoke, and it had been a valve or tube or something not clamped completely, which he fixed and no more smoke, but at the same time he added transmission fluid saying it was a little low and ever since then the check engine light has been on. My husband thought it may have been bad gas or water in the gas, so we filled the tank and added fuel injector cleaner. Still the light stayed on. I recently read that putting too much transmission fluid in would mess up the vehicle also, and I checked the stick and it is ever so slightly above the mark it is supposed to be at, but my husband said that would not cause the problem. And recently it has been "jumping" while driving. Feels like it may have trouble when shifting gears, or something. Also, a few times when I have first started the vehicle and as I'm pulling off it will completely stall and I have to put back in park and restart. Late last year I had a few bad experiences with mechanics. Saying they fixed it and a week later something else is wrong. So I don't trust mechanics anymore. Can someone help and tell me what is possibly wrong with my explorer?

 

[Glacier991]

Well what we need you to do is get the code read and tell us exactly what the code is, not what someone tells you it means. The light is saying the computer saw something out of where it expected to see it, and so it sets a numeric code. That code can be retireved and it can give us valuable clues. Also, slight overfilling of a transmission isn't going to hurt anything. Get the codes read and let us know.

 

[CMoore]

Okay, I went to Autozone and had them read the codes. He printed the codes for me and it show numbers of P1120, P1121, and P0121. They say "throttle position sensor out of range", "throttle position sensor circuit intgermittent high voltage" & "the pch has determined that the actual input from the throttle position sensor does not match the calculated the input gathered from other sensores ie: manifold absolute pressure sensor, idle air control motor position etc." The guy at autozone tells me I just need to change the throttle position sensor, says costs like $29.99. Could this be what causes it to "jump" like it has been, and for it to stall out on me at times?

 

[Alec]

If you had 3 TPS codes then yes, replace it. However, it'll probably be a bit more expensive than that on the later motor.

Also check the wiring. Could just be a bad wire or connection.