P0472

P0472-EXHAUST PRESSURE SENSOR 1 LOW





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

Theory of Operation

The Exhaust Gas Pressure Sensor is used to measure exhaust gas pressure in the exhaust manifold. The Powertrain Control Module (PCM) provides a 5-Volt supply to the Exhaust Gas Pressure Sensor on the sensor supply circuit. The PCM also provides a ground on the sensor return circuit. The Exhaust Gas Pressure Sensor provides a signal to the PCM on the Exhaust Gas Pressure Sensor Signal circuit. At key on, the readings for the exhaust gas pressure, intake manifold pressure and ambient air pressure are compared. This fault code occurs if the exhaust gas pressure reading is different from the other two. During normal engine operation EGR position and Boost Pressure Sensor readings are used to calculate an estimated exhaust pressure. If the difference between the estimated and the value read from the Exhaust Gas Pressure Sensor is above a calibrated threshold for a calibrated period of time then an error is recorded. The key-on portion of the rationality will light the MIL immediately after the diagnostic runs and fails. The rationality portion has to fail in two consecutive drive cycles for the MIL to become illuminated. If this fault becomes active the PCM will light the MIL light immediately. During this time the PCM uses an estimated exhaust gas pressure. The PCM turns off the MIL when the diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
Ignition on, engine not running.

- Set Condition:
The circuit voltage to the Powertrain Control Module (PCM) falls below 0.25 of a Volt for five seconds.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC

NOTE: If there are any 5-Volt supply DTCs present, repair those DTCs before proceeding.

1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 75 seconds.
5. Turn the ignition on.
6. With the scan tool, read DTCs.

Did the DTC return?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. CHECK THE (K355) EXHAUST PRESSURE SENSOR SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE




1. Turn the ignition off.
2. Disconnect the Exhaust Pressure Sensor harness connector.
3. Disconnect the PCM C1 harness connector.
4. Measure the resistance of the (K355) Exhaust Pressure Sensor Signal circuit between the Exhaust Pressure Sensor harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 3

No

- Repair the (K355) Exhaust Pressure Sensor Signal circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK THE (K355) EXHAUST PRESSURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND




1. Measure the resistance between ground and the (K355) Exhaust Pressure Sensor Signal circuit at the Exhaust Pressure Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the (K355) Exhaust Pressure Sensor Signal circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 4

4. CHECK FOR THE (K355) EXHAUST PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO THE (K916) SENSOR GROUND CIRCUIT




1. Measure the resistance between the (K355) Exhaust Pressure Sensor Signal circuit and the (K916) Sensor Ground circuit at the Exhaust Pressure Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (K355) Exhaust Pressure Sensor Signal circuit and the (K916) Sensor Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 5

5. CHECK THE EXHAUST PRESSURE SENSOR




1. Reconnect the PCM C1 harness connector.
2. Turn the ignition on.
3. While monitoring scan tool, connect a jumper across the (F857) 5-Volt supply circuit and the (K355) Exhaust Pressure Sensor Signal circuit at the Exhaust Pressure Sensor harness connector.

Did the scan tool display DTC P0473 active?

Yes

- Replace the Exhaust Pressure Sensor.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.