P1406

CIRCUIT DESCRIPTION

The PCM monitors the EGR valve pintle position input to ensure that the valve responds properly to commands from the PCM and to detect a fault if the pintle position sensor and control circuits are open or shorted. If the PCM detects a pintle position signal voltage outside the normal range of the pintle position sensor, or a signal voltage that is not within a tolerance considered acceptable for proper EGR system operation, the PCM will set DTC P1406.

CONDITION FOR SETTING THE DTC

^ EGR Feedback is less than 0.14 volt at any time.

OR

^ EGR Feedback is 0.4 volt greater or less than the EGR Closed Valve Pintle Position when the Desired EGR Pos is commanded to 0%.

OR

^ Actual EGR Pos is 20% greater or less than the Desired EGR Pos.

^ Any of the above conditions present for longer than 20 seconds.

ACTION TAKEN WHEN THE DTC SETS

^ The PCM will illuminate the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.

^ The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records data.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic has been run and passed.

^ The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

^ The DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

DIAGNOSTIC AIDS

Check for the following conditions:

^ Excessive deposits on EGR valve pintle or seat. Check for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick.

^ Poor connection or damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the EGR actual position display on the scan tool while moving connectors and wiring harnesses related to the EGR valve. A change in the display will indicate the location of the fault.

Important: If the EGR valve shows signs of excessive heat, check the exhaust system for blockage (possibly a plugged catalytic converter) using the Restricted Exhaust System Check.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused She DTC to be set occurs. This may assist in diagnosing the condition.


TEST DESCRIPTION

Number(s) below refer to the step number(s) on the Diagnostic Table.

2. Verifies that the fault is present.

3. If DTC P01406 will only set under certain conditions, the fault may be intermittent refer to Diagnostic Aids. If an intermittent wiring problem is not present, check for an open EGR ignition circuit to the PCM. Connect a test light to ground and probe the EGR ignition at the PCM harness connector. With the ignition ON, the test light should be ON. If not, repair the open in the EGR ignition circuit. If the test light is ON, check for a faulty connection at the PCM. If the connection at the PCM is OK and DTC P1406 continues to set, replace the EGR valve.