Service Engine Soon

Tiny
LADYHAWKJJ
  • MEMBER
  • 2001 PONTIAC 1000
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 75,000 MILES
My service engine soon light came on. I stopped at Auto Zone and this is it. Coolant temp is always low. The powertrain control module verifies that the engine is at a proper operating temperature. It was low on coolant and I put some in, however the light is still on. Am I supposed to reset it somehow. Or is there another problem. It did list some other possible causes. Thermostat defective, and ECI sensor defective. I drove the car 100 miles with the light on in one trip before I got the diagnostic, and the engine temp stayed below about 180. This is a 2001 Pontiac Grand Prix GT.
Tuesday, November 30th, 2010 AT 11:35 AM

14 Replies

Tiny
FIXITMR
  • MECHANIC
  • 9,990 POSTS
I'd try new thermostat.
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Tuesday, November 30th, 2010 AT 11:55 AM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
What was the actual code number?
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Tuesday, November 30th, 2010 AT 12:58 PM
Tiny
LADYHAWKJJ
  • MEMBER
  • 10 POSTS
The Autozone paper says the OEM number to Cross is P0128. Does anyone know where the thermostat is on this vehicle so that I can check the wires? Also, I drove for about 30 minutes with the heater on, and it never got hot like it would normally. It was just a little warmer than tepid. Don't know if that helps. Thanks, Judy
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Wednesday, December 1st, 2010 AT 12:12 AM
Tiny
WRENCHTECH
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Yes, a thermostat should fix that code. Follow the upper radiator hose to the thermostat housing.
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Wednesday, December 1st, 2010 AT 12:15 AM
Tiny
LADYHAWKJJ
  • MEMBER
  • 10 POSTS
A new development. I went to change the thermostat, and when I pulled off the plastic engine cover, I discovered that while I was camping over the long weekend, rats got up under there and started a nest, and chewed on the wires. The light had initially come on on the way home from the camping trip. I put together and re-taped the wires. Pretty sure that was the problem. I started the car, but the service engine light is still on.I didn't run it long. Is there anyway to reset it? Or should I just drive it awhile and see if it goes out? One wire which was made of of fine copper wires was pretty chewed up. I could splice in a new piece if needed. I HATE RATS!
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Thursday, December 2nd, 2010 AT 10:33 PM
Tiny
WRENCHTECH
  • MECHANIC
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I doubt rats set that code
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Thursday, December 2nd, 2010 AT 11:05 PM
Tiny
LADYHAWKJJ
  • MEMBER
  • 10 POSTS
No chance that the bared wires close to the thermostat could have caused the code? They could be the ones going to the ECI sensor or something. The timing is awful coincidental.
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Friday, December 3rd, 2010 AT 1:10 AM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
OK, fix it and find out.
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Friday, December 3rd, 2010 AT 1:15 AM
Tiny
LADYHAWKJJ
  • MEMBER
  • 10 POSTS
OK, I replaced the thermostat. The Service Engine light is still on. Do I have to drive it awhile for it to reset, or should that have happened right away?
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Saturday, December 11th, 2010 AT 3:41 PM
Tiny
LADYHAWKJJ
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Also, I took off the positive battery cable for 15 minutes, not only did that not work, my radio stations were still there. Going to try again with both cables.
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Saturday, December 11th, 2010 AT 4:32 PM
Tiny
LADYHAWKJJ
  • MEMBER
  • 10 POSTS
Problem solved. Went back to Autozone and borrowed their code reader. Used it to erase the existing codes. Ran the car, and it hasn't come back on. Yeah!
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Saturday, December 11th, 2010 AT 8:19 PM
Tiny
FIXITMR
  • MECHANIC
  • 9,990 POSTS
So you have heat now?
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Saturday, December 11th, 2010 AT 8:19 PM
Tiny
LADYHAWKJJ
  • MEMBER
  • 10 POSTS
Yes, my car is now toasty warm. Thanks.
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Wednesday, December 15th, 2010 AT 10:24 PM
Tiny
WRENCHTECH
  • MECHANIC
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Closing out question
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Monday, March 28th, 2011 AT 6:56 PM

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