OBD
P0738
TCM Engine Speed Output Circuit Low
What it means
P0738 means TCM Engine Speed Output Circuit Low.
Check these first
- A short to ground in the engine speed output wire
- A failed engine speed sensor
- Corrosion at the TCM connector
- A poor TCM ground
What to do next
- Read the engine speed output on a scan tool
- Test the output wire for a short to ground
- Check the sensor signal and connector
- Inspect the TCM ground
- Replace the TCM if the output stays low
- Clear the code and retest
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Updated
Generic SAE J2012 definition. Last updated 2026-10-10.