Code 36 - MAF Burn-Off Failure: Notes

The Mass Airflow (MAF) sensor measures the amount of air which passes through it. The ECM uses this information to determine the operating condition of the engine to control fuel delivery. Due to contaminates in the atmosphere, a residue may build up on the MAF sensor "hot wire". To maintain an accurate reading from the sensor, a burn-off cycle will occur when the ignition is turned off after the engine has been running a specified amount of time and engine is at operating temperature. The burn-off function takes place when the ECM grounds circuit No. 900 which energizes the MAF sensor burn-off relay. With the MAF sensor burn-off relay energized, voltage will be supplied to the MAF sensor terminal "D". Voltage will also be supplied through the normally closed set of contacts in the MAF power relay which will supply 12 volts to terminal "E" of the MAF sensor. During the burn-off cycle, the ECM monitors the 5-volt MAF signal line (circuit No. 998). The increase in temperature, up to 1000°F (538°C), on the MAF "hot wire" will be reflected as a voltage change on circuit No. 998. If this change is not reflected at the ECM, a Code 36 will be set in memory and the "SERVICE ENGINE SOON" light will come on the next time the vehicle is started.

1. This test will determine if the burn-off function is operative or if the code was set due to an intermittent condition.
2. Check for continuous 12-volt supply to burn-off relay.
3. Grounding circuit No. 900 should energize the burn-off relay and close the contacts.
4. With the burn-off relay energized, there should be 12 volts supplied to the MAF sensor on terminals "D" and "E" (circuits No. 993 and 994).