2012 Jeep Wrangler JK Factory Service Manual 28 - DTC-Based Diagnostics

P0406-EGR POSITION SENSOR CIRCUIT HIGH

P0406-EGR POSITION SENSOR CIRCUIT HIGH

For a complete wiring diagram, refer to the Wiring Information.


Theory of Operation

The Exhaust Gas Recirculation (EGR) Valve is opened by a motor located inside the EGR Valve. The pulse width modulated motor is controlled by the Powertrain Control Module (PCM). The EGR Valve also has an internal three wire 5-Volt EGR Position Sensor. This internal sensor reports the position of the valve back to the PCM over the EGR Position Sensor Signal circuit. The EGR system and Diesel Particulate Filter regeneration will be disabled when the fault is active.



Possible Causes

(K34) EGR POSITION SIGNAL CIRCUIT SHORTED TO VOLTAGE
(K900) SENSOR GROUND CIRCUIT OPEN/HIGH RESISTANCE
EGR VALVE
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


1. DTC IS ACTIVE

1. Ignition on, engine not running.
2. With the scan tool, select View DTCs.


Is the status Active for this DTC?

Yes


No


2. CHECK THE (K34) EGR POSITION SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the EGR Valve harness connector.
3. Disconnect the PCM C1 harness connector.
4. Remove the ASD Relay from the TIPM.
5. Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay Connector.
6. Turn the ignition on.
7. Measure the voltage of the (K34) EGR Position Signal circuit at the EGR Valve harness connector.


Is there any voltage present on either circuit?

Yes


No


3. CHECK THE (K900) SENSOR GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Remove the jumper wire and install the ASD Relay.
3. Measure the resistance of the (K900) Sensor Ground circuit between the EGR Valve harness connector and the PCM C1 harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


4. CHECK THE EGR VALVE

1. Reconnect the EGR Valve Assembly harness connector.
2. Reconnect the PCM C1 harness connector.
3. Turn the ignition on.
4. With the scan tool, erase DTCs.
5. Turn the ignition off.
6. Disconnect the EGR Valve Assembly harness connector.
7. Connect a jumper between ground and the (K34) EGR Position Signal circuit at the EGR Valve Assembly harness connector.
8. Turn the ignition on.
9. With the scan tool, select View DTCs.


NOTE: The scan tool should display a P0405-EGR Position Sensor Circuit Low DTC with the jumper in place.


Does the scan tool display the DTC as described above?

Yes


No


5. POWERTRAIN CONTROL MODULE

1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the EGR Valve and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Perform any Technical Service Bulletins that may apply.


Were any problems found?

Yes


No