Asked by Jul 05, 2016 at 06:27 PM about the 2006 Pontiac Grand Prix Base

Question type: Maintenance & Repair

this car sometimes will not start and other times the power drops down while
driving it.  We got a couple codes off of it.  P1125  and P2138.  I went to the
parts store a friend of mine owns and he said this car doesn't show a throttle
position sensor.  the other parts store said yes it does...2 of them.  How do
you tell which one is bad if there is 2 of them.  Or any help will be appreciated.

4 Answers


best bet is to change the throttle body assembly. not too expensive on amazon. if that doesn't work change the gas pedal. but since you said the car wont start sometimes it's more likely a bad throttle body position sensor. if money is tight cleaning the connectors with contact cleaner may help.


Best bet is not to just start randomly changing part hoping to miraculously solve a problem. Best bet is to do some more diagnosis to find the actual problem. Checking for trouble codes is a good start. Now its time to take it to a shop and have an actual technician evaluate what those codes mean and probably do some further diagnostics. A few dollars spent there will save you hundreds on un-needed parts.


theres nothing random about it. the codes have it fairly narrowed down. taking it to the shop to have it further diagnosed will be more than 4 times as expensive as changing a $150 part. I understand your point. but I thought the point of this website was for people who like fixing their own cars


You're right. There are times when it makes sense to just change out an inexpensive part instead of spending a lot of time and money looking further. I have my doubts that the type of diagnostics that are needed here would cost $600 though. And, as was noted there is considerable doubt about whether that's what's really wrong. The purpose of this site is to give guidance to a wide range of people who come here looking for help. Some are do it yourselfers, but many are simply people looking for help, and often the best help us "gurus" can give is to counsel them to seek professional help.

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