DTC 51

Code 51 Chart:

EGR System & REGTS Wiring Diagram:

CIRCUIT DESCRIPTION:

A Code 51 indicates that the Recirculated Exhaust Gas Temperature (REGT) Sensor has signaled to the ECM a temperature above or below the calibrated range.

TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.

1. Checks to see if the EGR valve diaphragm is seated at idle. Raising up on the valve should stagger the engine if the valve was not previously open, and EGR passages are not blocked. Temperature will be high if the valve is open at idle or low if passages are blocked.

2. Checks to see if the EGR valve diaphragm will function normally with engine vacuum.

3. Checks to see if sensor is supplied with 5.0 volts from the ECM.

4. Checks to see if the fault is a sensor or the ECM. The sensor range is from 40k ohms cold to about 10k ohms on a hot engine.