P1751 Transmission code whose meaning differs: a hydraulic malfunction on Honda and Acura, a control relay fault on Mitsubishi

Honda/Acura and Mitsubishi P1751

Severity not verified — if the car runs badly, have it inspected

The two meanings differ by make and the reports we read describe shifting trouble and an intermittent no-start, with no source that sets a safe driving limit.

It gets more serious if:

  • Inspect soon: The transmission shifts harshly, slips, shows warning lights or the vehicle intermittently will not start.

Source: how we rate severity

P1751 in short

P1751 has different meanings by make. On Honda and Acura it is a mechanical problem in the transmission hydraulic control system; on Mitsubishi it is the automatic transmission control relay. Reports describe shifting trouble or an intermittent no-start. We could not verify a safe driving limit, so get it scanned soon.

Honda and Acura reference lists define P1751 as a mechanical problem in the hydraulic control system involving shift solenoid B and the clutch pressure control solenoids. A 2001 Accord owner had the D4 and TCS lights and a shift problem with it.

Mitsubishi lists it as the transmission control relay. A 2003 Diamante dealer pointed to that relay for an intermittent no-start with P1751 stored.

Other makes use the number differently, and we could not confirm those meanings, so this page speaks only for Honda, Acura and Mitsubishi. A 2002 Montero Sport bulletin names the code but its summary does not give a repair.

Pick your make

P1751 is a manufacturer-specific code: its meaning depends on who built the car.

Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.

Most likely causes

  1. Hydraulic control or solenoid problem inside a Honda or Acura transmission

    Supported by vehicle data
    Why it ranks here
    Two reference lists define the code that way, and a 2001 Accord had a shift problem with P1751 and P0730.
    What would change this
    Rises with gear ratio codes and slipping. Falls if shifts are normal.

  2. Automatic transmission control relay (Mitsubishi)

    Supported by vehicle data
    Why it ranks here
    The reference list names the control relay and a Diamante dealer blamed that relay for an intermittent no-start.
    What would change this
    Rises if the relay fails a test or the no-start is intermittent. Falls if the relay tests good.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Note the make, read all transmission codes and note any gear ratio codes such as P0730.

    Low riskTool: OBD-II scan tool

    • IfHonda or Acura with P1751 and shift trouble

      It meansGo to the transmission shop check.

      Go to step 2

    • IfMitsubishi with P1751 and an intermittent no-start or shift problem

      It meansGo to the relay and shop check.

      Go to step 2

  2. Have a shop test the transmission control relay on a Mitsubishi, or the shift and clutch pressure solenoids and hydraulic pressure on a Honda or Acura.

    Best left to a shopTool: scan tool, multimeter

    Warning:Transmission parts are inside the case, and a loss of power can strand you; let a shop test it.

Symptoms

  • Check engine light on
  • Harsh or wrong shifts, D4 or TCS lights Gets more serious: stop and have it checked.
  • Intermittent no-start (Mitsubishi) Gets more serious: stop and have it checked.

How to fix

  1. Do not clear the code before a shop has read it; the stored data helps confirm which meaning applies.

On your vehicle

Honda

Mitsubishi

  • 8113Status unverified

    P1751 and service engine soon light

    2002montero-sport · NHTSA 631469

    Names P1751 with the check engine light on; the summary does not give the repair.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 80Status unverified

    Diagnosing P1751 with the service engine soon light on

    2002montero-sport · NHTSA 637076

    Diagnostic information for P1751; the summary does not give the repair.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

All Transmission codes

Sources and review

  1. NHTSA complaint 1999846: 2001 Honda Accord, P0730 and P1751 — NHTSA (owner complaint)
  2. NHTSA complaint 788545: 2003 Mitsubishi Diamante, P1751 — NHTSA (owner complaint)
  3. P1751 manufacturer-specific definitions — TroubleCodes.net (BAT Auto)
  4. Honda/Acura P1600 to P1895 OBD II code list — EricTheCarGuy
  5. Mitsubishi bulletin 8113: P1751 and service engine soon light — Mitsubishi Motors North America (via NHTSA flat-file summary)
  6. Mitsubishi bulletin 80: diagnosing P1751 with the service engine soon light on — Mitsubishi Motors North America (via NHTSA flat-file summary)
Last reviewed
Written by
Saurabh K.
Editorial review
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This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

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