Question about 2003 Cadillac CTS

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Message P1028 Heat Sensor or Thermostat problem,I was told by Dealer Cost to repair $1400.00 estimate only.We have conrolled heat in car re:temperature and same for Air Conditoning.Anti freeze OK. What are your thoughts? Thank you in advance John Russell @

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P0128 is the DTC for "coolant temperature too low for closed loop".
The computer knows what the Coolant temp should be and if it stays below regulated temperature for too long the code will set. This occurs more frequently in the winter when temperatures plummet.

The quickest and most reasonable solution would be to replace the engine thermostat, reset the DTC code and try again.
The biggest drawback for driving under this condition will be fewer miles per gallon as the engine needs higher temperatures for efficient combustion.

I also wouldn’t take it to the Cadillac dealer… in my humble opinion, they are trying to fleece you.

Posted on Feb 04, 2010


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Posted on Jan 02, 2017


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