P0652 - Sensor Reference Voltage Circuit Low
The P0652 code indicates that the Engine Control Module (ECM) has detected a low voltage condition on the 5-volt reference circuit that powers various sensors (e.g., throttle position, crankshaft position, manifold absolute pressure). This can be caused by a short to ground, a faulty sensor, or a damaged wiring harness. The ECM monitors this voltage and triggers the code when it falls below a specified threshold, potentially affecting multiple sensor readings and engine performance.
1. Most Common Causes
- Short to ground in the 5-volt reference circuit
- Faulty sensor (e.g., throttle position sensor, MAP sensor)
- Damaged wiring or connectors
- Corroded or loose electrical connections
- Failed ECM (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine stalling or rough idle
- Poor acceleration or hesitation
- Reduced fuel economy
- Other sensor-related codes may appear
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all codes and freeze frame data.
Step 2: Visually inspect the 5-volt reference circuit wiring and connectors for damage, corrosion, or loose connections.
Step 3: Disconnect sensors one by one while monitoring the reference voltage with a multimeter to isolate the short.
Step 4: If voltage returns to normal after disconnecting a sensor, replace that sensor.
Step 5: If no sensor is at fault, repair the wiring harness or replace the ECM if necessary.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause erratic engine behavior, stalling, or reduced power, which may lead to unsafe driving conditions.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, but can be higher if the ECM needs replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.