Engine Hot Lamp Output Control Circuit Malfunction
The P0655 code indicates a malfunction in the circuit that controls the engine hot warning lamp. This lamp is typically located on the dashboard and illuminates when the engine coolant temperature exceeds a safe threshold. The Powertrain Control Module (PCM) monitors the circuit for proper voltage and resistance. A fault can be due to a short, open, or high resistance in the wiring, a blown bulb, or a faulty PCM. This code does not directly indicate engine overheating but rather a problem with the warning system.
1. Most Common Causes
- Damaged, corroded, or disconnected wiring or connectors in the hot engine lamp circuit
- Short to ground or short to battery voltage in the lamp control circuit
- Blown fuse in the indicator lamp circuit
- Failed bulb or indicator lamp assembly
- Internal PCM failure (rare)
2. Symptoms You Will Notice
- Engine hot warning lamp does not illuminate when engine is overheating
- Engine hot warning lamp stays on constantly
- Check Engine Light may be on
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for other related codes.
Step 2: Visually inspect the engine hot warning lamp bulb and replace if burned out.
Step 3: Check the wiring and connectors for damage, corrosion, or loose connections.
Step 4: Use a multimeter to test for continuity and proper voltage in the circuit.
Step 5: If all else fails, test the PCM output or consult a professional for PCM replacement.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended because the engine hot warning lamp may not alert you to actual overheating, which can cause severe engine damage. Have it diagnosed promptly.
How much does it cost to fix?▼
Typically between $50 and $150, depending on the cause. A bulb replacement is cheap, while wiring repairs or PCM replacement can be more expensive.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.