P0737 - TCM Engine Speed Output Circuit Malfunction
The Transmission Control Module (TCM) monitors engine speed via a signal from the Engine Control Module (ECM) or a dedicated sensor. Code P0737 indicates that the TCM has detected an incorrect or missing engine speed signal, which can disrupt transmission shift timing and torque converter lockup. This is often due to wiring issues, faulty sensors, or communication problems between modules.
01. Most Common Causes
- Faulty engine speed sensor (crankshaft position sensor)
- Damaged wiring or connectors in the engine speed circuit
- Malfunctioning ECM or TCM
- Corroded or loose electrical connections
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or erratic shifting
- Transmission stuck in limp mode
- Poor acceleration or hesitation
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm code P0737 and check for related codes.
Step 2: Inspect wiring and connectors between the engine speed sensor and TCM for damage or corrosion.
Step 3: Test the engine speed sensor (crankshaft position sensor) for proper resistance and signal output.
Step 4: Check for communication issues between ECM and TCM using a scan tool.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with P0737 can cause transmission damage due to improper shifting or torque converter operation. Have it diagnosed promptly.
How much does it cost to fix?▼
Repair costs typically range from $50 to $150 for sensor replacement or wiring repair, but could be higher if the TCM or ECM needs replacement.