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OBD-II Code

P1404

Severity

Not yet reviewed

Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.

Can you drive it

We cannot say

Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.

Indicative cost (USD)

$40–$420

From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.

P1404 sets when the EGR valve fails to return to its closed (rest) position within the PCM's calibrated tolerance — typically the EGR pintle position sensor reads more than 5% open when the PCM has commanded 0% for longer than 5 seconds, or the valve takes more than 1.5 seconds to close after the command goes to zero.

How a shop works this

Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.

  1. Note every code that is set, not just this one.

    Codes that appear together usually narrow the cause faster than any one of them read alone.

  2. Read the freeze frame — the conditions the fault was recorded under.

    Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.

  3. Confirm the fault is current rather than history.

    Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.

  4. Then follow the diagnostic notes further down this page, in the order they are written.

    They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.

If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.

Common symptoms

  • Check engine light
Read the full diagnostic procedureP1404 sets when the EGR valve fails to return to its closed (rest) position within the PCM's calibrated tolerance — typically the EGR pintle position…

P1404 sets when the EGR valve fails to return to its closed (rest) position within the PCM's calibrated tolerance — typically the EGR pintle position sensor reads more than 5% open when the PCM has commanded 0% for longer than 5 seconds, or the valve takes more than 1.5 seconds to close after the command goes to zero.

Cheapest-first diagnosis

  1. scan-tool the EGR Position Actual vs Commanded PID at idle — commanded 0%, actual should read 0-2%; command 30% via bidirectional test and watch the actual track within 0.3 seconds.
  2. If the actual lags or sticks, the pintle is carbon-coked.
  3. Remove the valve and inspect the pintle seat — black carbon buildup that prevents full seating is the #1 cause and is almost always cleanable with a soft brass brush and throttle-body cleaner; do NOT use a wire wheel.
  4. If the pintle is clean and still sticks, the internal stepper motor is failing and the valve must be replaced.
  5. Expensive misdiagnosis: shops replace the valve at $250-400 when a 15-minute carbon clean would have fixed it — and on some platforms the new valve cokes up again within 6 months because the underlying problem is rich-running upstream that nobody addressed.
Vehicle-specific patterns2005-2010 Impala/Monte Carlo/Grand Prix 3.5L/3.9L LZ4/LZE/LZ9 is the textbook P1404 platform — the EGR pintle cokes from the high-EGR calibration com…
  • 2005-2010Impala/Monte Carlo/Grand Prix 3.5L/3.9L LZ4/LZE/LZ9 is the textbook P1404 platform — the EGR pintle cokes from the high-EGR calibration combined with short-trip driving (PIP4521 covers cleaning vs replace decision tree).
  • 2004-2008Malibu 3.5L sees P1404 by 70K miles routinely.
  • 2002-2007Trailblazer/Envoy 4.2L I6 throws P1404 from the EGR cooler weeping coolant into the valve, which mineralizes on the pintle.
  • 2007-2009Uplander/Terraza/Relay 3.9L sets P1404 from the same 3.5/3.9L coking pattern plus a known position-sensor internal failure.

Estimated repair$40 to $420.

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