P0471

P0471-EXHAUST PRESSURE SENSOR 1 PERFORMANCE





For complete wiring diagrams refer to Diagrams/Electrical.


Theory of Operation

The exhaust gas pressure sensor is used to measure exhaust gas pressure in the exhaust manifold. The Electronic Control Module (ECM) provides a 5-volt supply to the exhaust gas pressure sensor on the sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The exhaust gas pressure sensor provides a signal to the ECM on the exhaust gas pressure sensor signal circuit. This sensor signal voltage changes based on the pressure in the exhaust manifold. There are two parts to this fault code, a key on check and a rationality check. 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. This diagnostic is run 5 seconds after key on. During normal engine operation EGR position and Boost Pressure sensor readings are used to calculate an estimated exhaust pressure. If the difference between the value read from the exhaust pressure sensor and the estimated 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 ECM will light the MIL light immediately. During this time the ECM uses an estimated exhaust gas pressure. The ECM turns off the MIL when the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:

5 seconds after key on.

- Set Condition:

The exhaust gas pressure sensor reading at key on differs by a calibratable amount of pressure from the barometric pressure sensor and boost pressure sensor or the exhaust gas pressure sensor reading varies from an estimated value during normal engine operation.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.


1. EXHAUST GAS PRESSURE SENSOR TUBE

Remove the steel tube from the exhaust manifold to the exhaust pressure sensor port.

Is the tube free from debris?

Yes

- Go To 2

No

- Clean the tube and reinstall.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

2. AIR INLET/CHARGE AIR/EXHAUST GAS RECIRCULATION LEAKS

Check vehicle/engine for leaks of inlet air (air filter to turbocharger), Charge Air (Turbocharger to intake manifold), or EGR gasses (exhaust manifold to intake manifold)

Were there any leaks detected?

Yes

- Repair leak condition.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 3

3. EXHAUST GAS PRESSURE SENSOR

Turn ignition switch on.

Wait 5 seconds after ignition switch is turned ON

With the scan tool, read DTC's.

Is P0471 stored?

Yes

- Go To 4

No

- Replace the exhaust gas pressure sensor .
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

4. EXHAUST GAS PRESSURE SENSOR

With the scan tool, erase DTC's.

Start the engine and let it idle for 1 minute.

With the scan tool, monitor the exhaust gas pressure reading.

Does the value fluctuate slightly, indicating the sensor is not stuck?

Yes

- Repair complete.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Replace the exhaust gas pressure sensor .
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test