GM OBD Trouble Code 85

By Jim Taddei, May 1, 2009

OBD I Code 85 - PROM error

If the ECM detects an internal fault with the PROM code 85 will set. The PROM is a special "chip" that is installed in the ECM, based on the particular vehicle configuration.

Fault Code Description

  • 85 - PROM


  • Engine may not start
  • Poor engine performance

Common Problems

  • Internal fault with PROM
  • PROM incorrectly installed in ECM

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