Particulate Matter Sensor Protection Tube Performance Diagnostic Setting False DTC

The particulate matter sensor protection tube performance diagnostic may set a false DTC P1488 (Particulate Matter Sensor Temperature Circuit High Voltage) on some 2020 Silverado and Sierra trucks equipped with the 3.0L Duramax diesel engine (RPO LM2). The Check Engine MIL also may be illuminated.

If the vehicle has DTC P1488 set, check if the particulate matter sensor is loose in the exhaust pipe. If the particulate matter sensor is loose, follow the diagnostics in the appropropriate Service Information.

If the particulate matter sensor is properly torqued and DTC P1488 is set, test the exhaust for leaks using the GE-52250 Power Smoke Diagnostic Leak Detector. Since the sealing bladder cannot be installed in the tailpipe upstream of the exhaust cooler, it’s recommended to use duct tape to seal the cooler.

Repair any leaks as needed and replace the particulate matter sensor.

If the joint shown is leaking (Fig. 23), the clamp may have bottomed out before sufficient clamp load was applied to the joint. (Fig. 24) The clamp should be replaced if this condition exists.


Fig. 23


Fig. 24


Refer to #PIP5748A for additional information.


– Thanks to Robert Bastien

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