Just got a P1404 CNF Mod 10 code. I’m seeing this code is mfr specific but it looks like it points to EGR problem. Before I just replace the EGR valve, I wanted to ask if anything else in that system would cause the same code?

Thanks in advance,

Tom

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Home >> Buick >> 1998 >> LeSabre V6-3.8L VIN K >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P1404

P1404

Wiring Diagram:

CIRCUIT DESCRIPTION

The PCM monitors the EGR valve pintle position input to ensure that the valve responds properly to commands from the PCM. When the ignition switch is turned ON, the PCM learns the EGR closed valve pintle position. The PCM compares the learned EGR closed valve pintle position to the Actual EGR position when the EGR valve is commanded closed. If the Actual EGR position indicates that the EGR valve is still open when the PCM is commanding the EGR valve closed, DTC P1404 will set.


CONDITIONS FOR RUNNING THE DTC

^ No Throttle Position (TP) Vehicle Speed Sensor (VSS), Misfire, AT, Manifold Absolute Pressure (MAP) Idle Speed, Fuel Injector, Engine Coolant Temperature (ECT), (CKP) Crankshaft Position or Mass Air Flow (MAF) sensor DTC(*) set.

^ System voltage is between 10 volts and 16 volts.


CONDITIONS FOR SETTING THE DTC

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

^ The above condition is 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 disable EGR for the ignition cycle

^ 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 condition(*):

^ Excessive deposits on the 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 connections at PCM or EGR valve.

Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

^ Damaged harness.

Inspect the wiring harness for damage. If the wiring appears to be OK, connect J 39200 DMM and check circuit continuity while moving connectors and wiring harnesses related to the EGR valve. A change in the DMM display will indicate the location of the malfunction.

TEST DESCRIPTION

Number(*) below refer to the step number(*) on the Diagnostic Table:

2. Verifies that the malfunction is present.

4. If DTC P1404 will only set under certain conditions, the malfunction may be intermittent; refer to DTC P1404 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 P1404 continues to set, replace the EGR valve. Refer to EGR Valve Replacement.

14. 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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Thank you!

if you end up needing the EGR, i highly recommend OEM not the aftermarket junk. EGR valves are especially in this category. Somethings you can do whatever.. EGR valves for 3800 not so much

The best thing to do is read the circuit description and study it in conjunction with the diagrams. The flow charts are aptly called trouble trees because following them can land you in trouble.