Trouble code P1406 Failed EGR value, Open or short circuit condition
Also code P0301 misfire cylinder 1 Next steps? Information for replacing EGR value? 1997 Bonneville SE 105K
P1406 Code - EGR Valve Pintle Position Circuit
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 malfunction 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
Ignition 1 voltage is greater than 10 volts.
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 Position is commanded to 0%.
OR
Actual EGR Position is 20% greater or less than the Desired EGR Position.
Any of the above conditions are 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:
Open EGR ignition filter circuit.
An open in the EGR ignition filter circuit will cause EGR Position Error to vary erratically 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 connector. If not, locate and repair the open in the EGR ignition filter circuit.
Excessive deposits on EGR valve pintle or seat.
Remove the EGR valve and 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 Actual EGR 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 malfunction.
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set
TEST DESCRIPTION
Number(s) below refer to the step number(s) on the Diagnostic Table:
Verifies that the malfunction is present.
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, Actual EGR position may be erratic when compared to Desired EGR position. An open in the EGR ignition filter circuit will cause DTC P1406 to be set after an extended period of time.
If DTC P1406 will only set under certain conditions, the malfunction may be intermittent; refer to DTC P1406 Diagnostic Aids. If an intermittent wiring problem is not present, check for a poor connection at the PCM or the EGR valve. If the connections are OK and DTC P1406 continues to set, replace the EGR valve.
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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P0301 Code - Cylinder #1 Misfire Detected
A P0301 code means that the the car's computer has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #1.
Symptoms may include:
the engine may be harder to start
the engine may stumble / stumble, and/or hesitate
other symptoms may also be present
Causes: A code P0301 may mean that one or more of the following has happened:
Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer
Possible Solutions:
If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.
Check it and keep us updated.
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