P0488

DTC P0488

CIRCUIT DESCRIPTION
The engine control module (ECM) monitors the position of the exhaust gas recirculation (EGR) valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. This voltage varies depending on the position of the EGR valve. The ECM interprets this voltage as the position of the EGR valve. When the ignition switch is turned ON, the ECM records the minimum value of the EGR valve position sensor which is the learned closed position. If the ECM detects a difference between the actual closed EGR position and the learned closed position of the EGR valve, DTC P0488 sets.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P0488 Exhaust Gas Recirculation (EGR) Closed Position Performance

CONDITIONS FOR RUNNING THE DTC
- DTCs P0112, P0113, P0405, P0406, and P0502 are not set.
- The ambient air temperature is more than 3°C (37°F).
- The engine is running.
- The desired EGR position is 0 percent.
- The ignition voltage is between 11.7-16 volts.
- DTC P0488 runs continuously once the above conditions are met.

CONDITIONS FOR SETTING THE DTC
- The ECM detects a difference of more than 10 percent between the actual and the learned position of the EGR valve.
- The ECM detects this failure for 40 consecutive times out of 40 test samples.
- The above failure must fail 3 sets of the 40 test samples. Each set of test samples are separated by more than 5 seconds with the desired EGR position being more than 30 percent.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

TEST

Steps 1-3:

Steps 4-8:

Steps 9-13:

Steps 14-15: