08 aura ect sensor or thermostat issue

[callitandrea]

My temp gauge stops working and ac won't work. However, it will start working and ac and everything works fine. The car isn't getting hot. I went to auto zone and had them put the scanner thing on it. I got back error codes p0013, p0128, p1682. There is 130000 miles on the car. How do I determine if it's the ect or the thermostat?

[fdryer]

P0128 Coolant Temperature Below Thermostat Regulating Temperature

https://www.obd-codes.com/p0128

P0128 usually points to t-stat running cooler than rated. Replace it.

The easiest way to know the difference between a faulty t-stat and coolant sensor is to use a reader capable of displaying live data. Other than a poorly chosen coolant sensor used in the S-series from '91-'01 with virtually all failing, Saturn issuing a service bulletin around 2000 to replace them, all Saturn models use the brass sensor. The faulty one was made of plastic, cracked from the temperature extremes and caused many problems. Yours is brass.

To determine temperature sensor operation is to display cold engine temps before starting. Temps should be close to outside temps. If there's a large difference between outside temps and sensor displayed value, the sensor and/or wiring are suspect Second reading should be after a full warm up, expecting between 185F-200F. The second reading with operating temps verifies sensor operation. Most t-stats are calibrated for around 195F as higher temps coincides with better emissions control. If cold engine temps coincide with outside temps, the warm engine temperature may display less than 185F to indicate a worn t-stat.

Several members here including myself with different models having the same P0128 code replaced their t-stat to correct this error.

[bmp93]

I had the issue last year and it was the thermostat. One of the seals on it had deteriorated and was letting a small amount of coolant pass through when the thermostat was closed. This was enough to tell the computer that something wasn't quite right, leading to the issues you mentioned appearing intermittently. Replacing it solved all of my issues.

If you plan on replacing the thermostat yourself, I found that removing the passenger side headlight made it much easier to access.

[pukaka]

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