H3 p0128 code and generation problem

[jaystylez15]

i had a check engine light come on i had the auto part store check it out they gave a code of p0128, i know it has to do with the temperature sensor etc but when i am driving and coming to a stop my dome lights seem to dim and also my dash board lights. also when i am in process of parking or turning my steering wheel at low speeds it turns off seems like its missing some torque or power. not sure if this has to do with this sensor any insight???

 

[digglesworth]

Where's your temp gauge sitting when your trucks good and warmed up? Mine threw that code and wouldn't warm up to over 1/4 on the temp gauge. It was a thermostat that was stuck open. Replaced it and it's good now. Fully warms up to just over half. Ive heard if the truck can't fully warm up, it's like driving around with the choke on.

As far as the lights dimming, check your battery terminals. Stock ones are known for being flaky.

 

[alrock]

The lights and sensor issues are likely unrelated. The power brake booster is electric and the H3 alternator is not always on. Thus, they heavy draw by the booster causes a momentary drop in electricity, giving you that dimming.

Nonetheless, the first place to start is with the battery terminals.. Make sure they are clean and tight. Poor connections or a weak battery can cause all kinds of issues.

What turns off at low speeds-the engine?



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[jaystylez15]

yes the engine shuts off completly and i have to turn the vehicle back on. not sure what it can be now being you said that sensor and my hummer shutting off is unrelated.

 

[alrock]

P0128 is a bad thermostat - that's a pretty straightforward fix. It could mean other things, but one should start with the most obvious problem first. And, like in any car, they do fail.

You are more than likely going to be taking this to a mechanic anyway so it may be good to start with that repair and ask them to troubleshoot the stalling. What year is your vehicle, how many miles are on it? Were any other codes present?

Long shot, but take a look at your serpentine belt. Is it shiny or in otherwise poor condition? I'm wondering if your power steering (or another belt driven item) is failing, causing a drag on the system.

 

[jaystylez15]

2006 h3 127000

yea going to get it checked out this weekend hopefully

 

[alrock]

It might be good to get a compression test done on the engine as well to verify that it's running properly. Has the cylinder head ever been replaced on this engine?