Error code

OBD2 P0729

OBD2P0729
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Gear 6 Incorrect Ratio.

Severity

moderateThe vehicle can be driven, but performance may suffer and the issue could worsen over time.

Summary

P0729 indicates an incorrect gear ratio in Gear 6 of the transmission. This code suggests that the input and output speeds are not matching as expected.

Symptoms

  • Lack of power
  • Slow speeds
  • Transmission slipping
  • Erratic shifting
  • Harsh shifts

Common Causes

  • Low transmission fluid level
  • Dirty transmission fluid
  • Transmission oil leak
  • Transmission clutch problems
  • Low oil pressure
  • Faulty transmission control module (TCM)
  • Damaged or dirty speed sensors
  • Corroded connections or pins
  • Wiring issues

Diagnosis

  1. Check for other transmission codes.
  2. Inspect and top up transmission fluid level.
  3. Visually inspect the transmission housing for damage or leaks.
  4. Test oil pressure in each gear.
  5. Check resistance values of speed sensors.
  6. Inspect wiring circuits for continuity, shorts, and opens.
  7. Back probe TCM connector to check electrical values.

Fixes

  • Replace faulty transmission components or repair damaged wiring.

FAQ

What should I do if the P0729 code persists after checking fluid levels?

If the issue continues, it may indicate a more serious problem such as internal transmission damage or faulty sensors. Consider taking your vehicle to a professional for further diagnosis.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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