Error code

OBD2 P0738

OBD2P0738
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

TCM Engine Speed Output Circuit Low.

Severity

moderateCan drive but may experience transmission issues. It's recommended to address the issue promptly.

Summary

P0738 indicates that the TCM Engine Speed Output Circuit is reporting low values, which can affect transmission performance and shift timing.

Symptoms

  • Driveability issues
  • Enters 'limp' mode
  • Will not upshift (Stuck in low gear)
  • Low vehicle speed
  • High RPMs
  • Transmission slipping in and out of gear
  • Poor engine performance

Common Causes

  • Corroded or damaged wiring
  • Loose or corroded connections
  • Defective crankshaft position sensor (CPS) and/or circuit
  • Faulty TCM
  • Damaged pins in modules
  • Low system voltage

Diagnosis

  1. Check system voltages and fluid levels.
  2. Inspect CPS sensor for damage or corrosion.
  3. Examine TCM and its harness connections.
  4. Verify specific circuit electrical values using a multimeter.
  5. Test TCM functionality with manufacturer-specific tools if necessary.

Fixes

  • Replace defective crankshaft position sensor (CPS) or repair wiring issues.

FAQ

What does P0738 mean?

P0738 indicates a low signal from the TCM Engine Speed Output Circuit, which can affect transmission performance.

How do I fix P0738?

Fixes may include repairing or replacing damaged wiring, fixing loose connections, and replacing a faulty CPS sensor.

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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