I cant find this code but my 02 is throwing it. PLease help

 

It points to a C-6 code for coolant temp not getting hot enough, fast enough. Why you would have that code in a C-5, I have no clue. Do you have a 160 degree thermostat?

 

DTC P0128
Circuit Description

An engine coolant temperature (ECT) sensor monitors the temperature of the coolant. This input is used by the powertrain control module (PCM) for engine control, and as an enabling criteria for some diagnostics.

The air flow coming into the engine is accumulated and used to determine if the vehicle has been driven within the conditions that would allow the engine coolant to heat up normally to the thermostat regulating temperature. If the coolant temperature does not increase normally or does not reach the regulating temperature of the thermostat, diagnostics that use ECT as enabling criteria, may not run when expected. This DTC will only run once per ignition cycle within the enabling conditions.

If the PCM detects the calibrated amount of air flow and engine run time have been met and the ECT has not met the minimum thermostat regulating temperature, DTC P0128 sets.
Conditions for Running the DTC

* DTCs P0101, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0125, P0500, P0502, P0503 are not present.
* The start up engine coolant temperature is less than 70°C (158°F).
* The intake air temperature (IAT) sensor parameter is between -7 to +55°C (+19 to +131°F).
* The engine is running between 120-1,370 seconds.
* The vehicle speed is more than 8 km/h (5 mph) for more than 2.5 kilometers (1.5 miles).
* The mass air flow (MAF) is between 15-75 g/s with the average more than 14 g/s.

Conditions for Setting the DTC

* The calibrated amount of engine run time has been met.
* The calibrated amount of engine air flow has been met.
* The calibrated vehicle speed and distance have been met.
* The calibrated minimum engine coolant temperature of 75°C (167°F) has not been met.

Action Taken When the DTC Sets

* The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
* The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

* The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
* A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
* A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
* Clear the MIL and the DTC with a scan tool.

 

Excellent info there...cool.

 

I did notice a couple of times that the car was running around 170 degrees after ten minutes of run time, but has ran at normal temps regularly after that. Could it still be the thermostat and thanks for the replies mark, dgrant, and 8vette7

 

I am guessing here that your thermostat isn't closing all the way when it cools down therefore when you start up again in the mornings, its not heating up fast enough.

 

yeah i clear it and sometimes it doesnt come back but its done it four or five times. Car has run a bit cool a few times which i thought was weird. Didnt do it last year during cold weather, she ran normally so.......new thermostat?

 

Thermostat is the most obvious thing. Put in a regular thermostat, clear the code and see if it comes back.

 

thanks guys will change it in a few days!!!

 

Why abandon the 160 thermostat? Just because of a code? Can we tune out the P0128 using HP Tuners? I just got this one also (and have the 160 thermo), and I discovered the Cat code was sitting in there too. I guess I tuned out the Cat Overtemp code, it still throws but does not set the Check Engine light.