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OBD-II Code

P1491

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)

$0–$420

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

P1491 on Honda is EGR Valve Lift Insufficient, set when the PCM commands the linear-solenoid EGR valve to a specific lift position and the integrated EGR lift sensor reports actual lift more than about 25 percent below commanded for several seconds during the EGR self-test (typically run at 1500 to 3000 rpm under light load).

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 procedureP1491 on Honda is EGR Valve Lift Insufficient, set when the PCM commands the linear-solenoid EGR valve to a specific lift position and the integrated…

P1491 on Honda is EGR Valve Lift Insufficient, set when the PCM commands the linear-solenoid EGR valve to a specific lift position and the integrated EGR lift sensor reports actual lift more than about 25 percent below commanded for several seconds during the EGR self-test (typically run at 1500 to 3000 rpm under light load). On Honda's design the EGR valve, lift sensor, and solenoid are a single assembly mounted on the intake manifold, and the most common failure mode by a wide margin is carbon packing the valve seat so the pintle can't physically reach its commanded position.

Cheapest ladder

  1. remove the EGR valve (two bolts, one connector on most D-, F-, and J-series Hondas), inspect the pintle and seat for thick black carbon, and clean with carb cleaner and a brass brush; do not soak the electrical lift sensor.
  2. While the valve is off, ream the EGR passages in the intake manifold with a wire brush because plugged passages cause the same code.
  3. Live data: with HDS, monitor EGR Lift Command vs EGR Lift Actual at 2500 rpm; healthy operation tracks within 0.3V. The expensive misdiagnosis is replacing the $200 to $350 EGR valve when a 30-minute cleaning plus passage reaming restores function.
Vehicle-specific patternsHonda Accord F22B and F23A (1994-2002) is the most common P1491 platform; the EGR passages in the intake manifold pack with carbon by 120k miles and…
  • 1994-2002Honda Accord F22B and F23A is the most common P1491 platform; the EGR passages in the intake manifold pack with carbon by 120k miles and require physical reaming through the intake's threaded plugs.
  • 1999-2004Honda Odyssey J35A V6 sees P1491 from EGR carbon plus a known TSB on the EGR valve assembly.
  • 1996-2005Honda Civic D16Y8 and D17 typically sets P1491 from the same carbon-packing pattern, easily cleaned.
  • 2000-2001Honda CR-V B20Z2 sets P1491 most often from a failed EGR lift sensor potentiometer track within the valve assembly.

Estimated repair$0 to $420.

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