Fuel Supply Heater Control Circuit/Open
The P2687 code indicates that the Powertrain Control Module (PCM) has detected an open or malfunction in the control circuit of the fuel supply heater. This heater is used in diesel engines to warm the fuel in cold conditions, preventing gelling. An open circuit means there is a break in the electrical path, which can be caused by a faulty heater element, damaged wiring, or a failed relay.
1. Most Common Causes
- Open or shorted fuel heater element
- Damaged wiring or connector in the heater circuit
- Faulty fuel heater relay or fuse
- Failed PCM (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Hard starting in cold weather
- Poor engine performance or stalling when cold
- Fuel gelling in extreme cold
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for related codes.
Step 2: Visually inspect the fuel heater wiring and connector for damage or corrosion.
Step 3: Test the fuel heater resistance with a multimeter (should be within spec).
Step 4: Check the fuel heater relay and fuse for proper operation.
Step 5: If all else is fine, test the PCM output to the heater circuit.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe to drive in warm weather, but in cold conditions the fuel may gel, causing stalling or no-start. It's best to repair promptly.
How much does it cost to fix?▼
Repair costs vary from $150 to $400 depending on the cause (e.g., replacing the heater element vs. wiring repair).
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.