2004 Mazda 323 Check engine light code PO128

2004 MAZDA 323
37,000 MILES • 4 CYL • 2WD • MANUAL
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DRPR1
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My Mazda 3 is throwing a PO128 code. I cleared it just to see if it was a random occurance but back it came. Is the thermostat faulty or could this be a defective sensor?

Also, I am looking for a service manual for this vehicle. I prefer a book rather than on line. My search has turned up no leads.
Feb 18, 2008 at 10:51 PM
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BLACKOP555
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P0128 is a obd code for coolant temperature bellow threshold.

it means that your coolant temp sensor CTS also known as Engine temp sensor ETS is no good and needs to be replaced.

to test it measure the resistance and compare it with the IAT intake air temp sensor and the resistance should be the same.

service manuals can be found at auto part stores nationwide, if you talk to them they can order you a book for your mazada, also check with the dealership.
Feb 19, 2008 at 9:11 AM
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DRPR1
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O.K. Thanks. So it is the sensor and not the thermostat.

Tried auto parts stores on the manual and on line. No luck on either. Apparently the only manual for this car is from the dealer at $150.
Feb 24, 2008 at 6:38 PM
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