P0729 OBD-II: Gear 6 Incorrect Ratio

P0729 Severity

Urgent

Should you fix P0729 yourself?

Identifying an OBD code is just the start of a complete diagnostic routine. Most trouble codes are caused by a sensor reporting a value that is out of range. Just replacing a sensor may not fix underlying issues. Be sure to understand the code, the part or system in your car that the code refers to, and the risks of delaying professional repair.

Proper diagnosis will save you time and money on unnecessary repairs.

Urgent codes indicate immediate action is necessary. These are urgent and significant malfunctions that can cause severe damage to the vehicle or harm the driver and passengers.

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What causes OBD-II fault code P0729?

The Input Speed Sensor tells the Transmission Control Module (TCM) how fast the engine is spinning so the correct gear can be engaged. The Output Speed Sensor tells the Transmission Control Module (TCM) how fast the output shaft of the transmission is spinning so it can verify the correct gear is engaged. The TCM compares both signals to verify the transmission is in the desired gear. If it is determined that the transmission is not in the desired gear, the engine control module (PCM) or TCM will set code P0729.

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What Does P0729 Code Mean?

OBD-II Code P0729 is defined as a Gear 6 Incorrect Ratio

The Input Speed Sensor tells the Transmission Control Module (TCM) how fast the engine is spinning so the correct gear can be engaged. The Output Speed Sensor tells the Transmission Control Module (TCM) how fast the output shaft of the transmission is spinning so it can verify the correct gear is engaged. The TCM compares both signals to verify the transmission is in the desired gear. If it is determined that the transmission is not in the desired gear, the engine control module (PCM) or TCM will set code P0729.

P0729 Symptoms

  • Increased fuel consumption
  • Transmission may not shift properly

Common Problems That Trigger the P0729 Code

  • Internal transmission failure
  • Powertrain Control Module (PCM) failure
  • Transmission Control Module (TCM) failure
  • Transmission fluid level is low
  • Transmission valve body failure
  • Wiring issue

Common Repairs Needed for the P0729 Code

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