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P0720

Output Speed Sensor Circuit Malfunction

The transmission output speed sensor signal is missing or implausible. The TCM uses this signal together with input speed to determine actual gear ratio; many vehicles also use it as a backup vehicle speed signal for the cluster and ECU.

  • Check engine light: Yes
  • Emissions related: No
  • Repair difficulty: hard

Symptoms

  • Check engine or transmission warning light on
  • Harsh, delayed, or missing shifts
  • Possible limp mode (locked in one gear)
  • Slipping or shuddering during gear changes

Common causes

Ordered by how often each turns out to be the cause.

  • Output speed sensor failedCommon
  • Wiring or connector faultPossible

Parts involved

  • Transmission Output Speed Sensor
  • Transmission Output Speed Sensor Wiring

P0720 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.