Hi everyone, I'm new here. Transferred over from trailvoy. I have a recurring problem that I'm hoping to get some help with. I've seen some similar discussions, but my case is a little different so I thought I'd start a new thread.
First off, 2003 trailblazer LT 4x4 4.2 I6. 102,000 miles.
I'll start with a little history, bought the car with 45000 miles, I've had the P0171 code pop up a few times since I've had the vehicle. The past couple times, changing the upstream O2 sensor fixed the problem. Each time the code occurred, it would be accompanied by high idle RPMs, specifically 900 RPMs. Just replaced the Upstream O2 sensor 10000 miles ago with an AC Delco sensor. That fixed the problem until now.
Now I'm getting the two codes P0171 and P0172. The engine will idle high at 900 for a period of time and then go down to normal after a bit of driving. The check engine light will come on and then go off. The engine is also running a bit hot, when the idle is high. It's about 2 ticks to the right of 210. Normally it's always just about right on 210.
I took the vehicle to a mechanic and they said both O2 sensors were operating normally. They suggested there was a vacuum leak somewhere and that I should bring back in a week and they will take another look. They also cleaned the throttle body.
I don't know a great deal about fixing engines so I don't know that I'll be able to diagnose anything on my own. I'm debating whether to take the vehicle to the dealership (not excited about that) or go back to the same mechanic.
Any suggestions or help would be appreciated. Thanks!
-Will
P.S. I forgot to add that the first time I read the codes about 3 days ago, there were about 24 codes that came up. I erased them and took the car to the mechanic. The only codes that came back up were the two I mentioned. Unfortunately I didn't write them all down, but there were some weird ones in there that didn't make any sense, like a brake light malfunction and all my brake lights work fine... Could there be some electrical problem or problem with the computer?
First off, 2003 trailblazer LT 4x4 4.2 I6. 102,000 miles.
I'll start with a little history, bought the car with 45000 miles, I've had the P0171 code pop up a few times since I've had the vehicle. The past couple times, changing the upstream O2 sensor fixed the problem. Each time the code occurred, it would be accompanied by high idle RPMs, specifically 900 RPMs. Just replaced the Upstream O2 sensor 10000 miles ago with an AC Delco sensor. That fixed the problem until now.
Now I'm getting the two codes P0171 and P0172. The engine will idle high at 900 for a period of time and then go down to normal after a bit of driving. The check engine light will come on and then go off. The engine is also running a bit hot, when the idle is high. It's about 2 ticks to the right of 210. Normally it's always just about right on 210.
I took the vehicle to a mechanic and they said both O2 sensors were operating normally. They suggested there was a vacuum leak somewhere and that I should bring back in a week and they will take another look. They also cleaned the throttle body.
I don't know a great deal about fixing engines so I don't know that I'll be able to diagnose anything on my own. I'm debating whether to take the vehicle to the dealership (not excited about that) or go back to the same mechanic.
Any suggestions or help would be appreciated. Thanks!
-Will
P.S. I forgot to add that the first time I read the codes about 3 days ago, there were about 24 codes that came up. I erased them and took the car to the mechanic. The only codes that came back up were the two I mentioned. Unfortunately I didn't write them all down, but there were some weird ones in there that didn't make any sense, like a brake light malfunction and all my brake lights work fine... Could there be some electrical problem or problem with the computer?