Good afternoon,
The most common issue for this is the EGR valve has carbon on the end of it not allowing to close fully.
Description below.
Roy
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.
CONDITIONS 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 10% 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 fault.
- 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:
- Open EGR Valve ignition positive voltage circuit.
An open in the EGR Valve ignition positive voltage circuit will cause EGR Pos. Error to be erratic while the EGR valve is operating. With the ignition ON, a test light should illuminate when connected between ground and the EGR ignition filter circuit at the PCM connection If not, locate and repair the open in the EGR Valve ignition positive voltage circuit.
- 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.
- EGR valve icing.
An EGR valve that sticks due to icing can cause DTC P1406 to be set. If DTC P1406 sets during extreme cold ambient conditions and the DTC P1406 diagnostic table does not isolate the cause of the malfunction, EGR valve icing is very likely the cause. The EGR valve should start operating normally once the engine has reached operating temperature.
TEST DESCRIPTION
Number(s) below refer to the step number(s) on the Diagnostic Table:
2. Verifies that the fault is present.
3. Verifies that the fault is present.
4. The PCM contains a recirculation diode which filters the EGR ignition feed for the EGR valve. The recirculation diode is connected to the ignition filter (EGR ignition feed) circuit. If the ignition filter circuit is open, EGR actual position may be erratic when compared to EGR desired position. An open in the EGR ignition filter circuit will cause DTC P1406 to be set after an extended period of time.
5. If DTC P1406 will only set under certain conditions, the fault may be intermittent; refer to DTC P1406 Diagnostic Aids. If an intermittent wiring problem is not present, check for a faulty connection at the PCM or the EGR valve. If the connections are OK and DTC P14O6 continues to set, replace the EGR valve. Go to EGR Valve.
32. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.
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Sunday, March 17th, 2019 AT 5:27 PM
