Hard Trouble Code E37: Notes

NOTE: If this code is not displayed during second pass of diagnostic codes, it is an intermittent failure and cannot be diagnosed using this procedure.

Trouble code E37 indicates that MAT sensor signal voltage is too low. This situation can be observed in engine data display parameter "P.0.5" as reading of 142-151°C. Possible causes of this condition are: Shorted MAT sensor, defective wiring, terminals, etc., or ECM is not able to process signals properly.

NOTE: The following step numbers refer to the numbers in the accompanying flow chart(s).

If opposite condition (open MAT signal) can be created, the self-diagnostics can be used to detect failure by displaying engine data parameter P.0.5. With opposite condition created, parameter "P.0.5" should display reading of B40°C to B35°C. To create open sensor signal, disconnect MAT sensor connector. If reading is now B40°C to B35°C, ECM and wiring harness are okay. Fault must be in MAT sensor itself.
If reading is B34°C or greater, then there is a short to ground in wiring harness or ECM.