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P1431

Misfire Monitor Disabled Unable to Learn Trigger Wheel Profile.

  • Ford
  • Powertrain
  • Manufacturer code
  • Low severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
4
AreaAuxiliary emission controls
31
FaultThe specific fault in that area

What it means

On Ford, P1431 means the engine control module could not learn the crankshaft trigger wheel profile, so the misfire monitor has been disabled. The module normally learns small differences in the trigger wheel tooth spacing during a profile learn, typically on a deceleration fuel cut-off, and uses that to detect misfires accurately. If the learn does not complete or the crankshaft signal is poor, the code sets and misfire detection is not available.

Symptoms

  • Malfunction indicator lamp on
  • No obvious driveability change in many cases
  • Misfire monitor not completing on an emissions or readiness check
  • Possible rough running or hesitation if a real crank signal fault is present
  • Other crankshaft or misfire codes stored alongside

Possible causes

  • Trigger wheel profile never learned after battery disconnect, module reset or module replacementlikely
  • Learn procedure not completed because the drive conditions (warm engine, deceleration fuel cut-off) were not metlikely
  • Faulty or erratic crankshaft position sensor signalpossible
  • Damaged wiring, poor connector contact or interference on the crankshaft sensor circuitpossible
  • Damaged or dirty trigger wheel or sensor mounting problemrare
  • Engine control module fault or outdated software, depending on model and enginerare

How to diagnose

  1. Read all stored and pending codes and the freeze frame data, noting any crankshaft, camshaft or misfire codes alongside P1431
  2. Ask whether the battery was disconnected, the module reset or replaced, or the engine recently worked on before the code appeared
  3. Inspect the crankshaft sensor wiring and connector for damage, corrosion, chafing or oil contamination
  4. Check the sensor is correctly seated and secure, and look at its tip for debris or damage
  5. View live crankshaft and camshaft signal data for dropouts or erratic readings during cranking and running
  6. Check the trigger wheel for damage or missing teeth where it can be inspected, as access depends on model and engine
  7. Clear the code and carry out the manufacturer's profile learn drive, following the procedure for that engine, then recheck for the code returning
  8. Check for applicable software updates for the module on that model

How to fix

  • Complete the manufacturer's trigger wheel profile learn procedure so the module can learn the profile
  • Repair or replace damaged crankshaft sensor wiring or connectors
  • Replace the crankshaft position sensor if its signal is faulty
  • Repair or replace a damaged trigger wheel or correct sensor mounting
  • Update or replace the engine control module only if testing confirms a module or calibration fault

Can I keep driving?

Low severity

The car can normally be driven while you book it in, as this code mainly disables misfire detection. If the engine runs roughly or other crankshaft or misfire codes are present, have it checked sooner.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

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