P0128 error code came on after I just had oxygen, camshaft, crankshaft sensors replaced, new brakes, & tune up

  • 106,000 MILES
Bare w/ me cause I know nothing about cars but im tired of possibly getting taken advantage of by mechanics! But about 3 weeks ago I brought my car to Pep boys cause my check engine light was on and it wasn't running right. I had run the code prior to that and can't remember the exact code but it had something to do with the sensors. They basically told me it was gonna be $700 to fix & were really rude & unhelpful to me & barely explained what needed to b done but I decided to just trust them & that they weren't ripping me off. According to the receipt the things they did was replaced spark plugs, air filter installation, replaced camshaft position sensor, crankshaft sensor, oxygen sensor. But then as I was driving home my brakes were suddenly making awful grinding noises that they were not making before so I went to Firestone auto center 2 days ago 2 get a free brake analysis and they were very nice to me, they explained everything I needed done in terms I understood and were honest about what I had to get done ASAP and what could wait ('I also asked them if Pep boys could have done anything to cause this but they said most likely no). Everything they did was replace all the front brake pads, rotors, & left caliber, brake fluid exchange, 2 new tires, & a courtesy check which checked all my fluid levels, alignment, etc. Which they said was all fine. But tonight my check engine light came on again! The code was p0128 which says its a problem with the coolant thermostat! Does anyone know if this could've been caused by any of the stuff I just had done to my car cause I'm not sure if I should go complain to Pepboys or Firestone? And is this gonna cost a lot more money cause I don't know if my cars even worth all this?
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have the same problem?
Monday, October 8th, 2012 AT 7:16 AM

1 Reply

If the first mechanic would have done something to the coolant temperature sensor the Engine Computer would have detected it right away and turned on the Check Engine light before the car left their shop.

I can't speak to the cost of the first service but a coolant temperature sensor installed for a Chrysler product is around $40.00 not including any diagnostic time. The code you have though suggests it's not a failure of the sensor, which is rare. It sounds more like the thermostat is opening too quickly and not letting the engine reach proper operating temperature. Depending on which engine you have, the thermostat is more time-consuming to replace than the temperature sensor.

This might not apply but you should be aware that there is a long list of things that must occur for a diagnostic code to set. One of those things is certain other codes can not already be set in memory. That's because the computer compares many sensor readings and other things to each other to figure out when something is wrong. As an example, it knows that when the engine has been off for more than six hours the intake air temperature sensor and the coolant temperature sensor had better be reading the same temperature. If there is already a code set for one of them, the computer has nothing to check the other one against so it can't set certain codes related to it. That is real frustrating to GM owners and their mechanics. If an anti-lock brake problem is ignored long enough, a second problem can develop but the second code won't set until right after the first problem is repaired. No one had any idea there was a second problem waiting to set a code. The mechanic is frustrated because he has to tell you more diagnosis and parts are needed beyond the original estimate, and you're frustrated because you're certain the mechanic is ripping you off.

I'm pretty sure your two problems aren't related though because it wouldn't have taken three weeks for the new code to set. If the thermostat really is all that's wrong you should notice the air from the heater is not as hot as normal. Also, if you have a temperature gauge on the dash, it will be reading lower than normal.
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Monday, October 8th, 2012 AT 7:48 AM

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