What Does P2689 Mean?
The PCM has detected abnormally high voltage in the fuel supply heater control circuit. This indicates a short to power or an open ground circuit that prevents the PCM from properly controlling the fuel heater.
Common Causes
35%
Wiring shorted to battery voltage in fuel heater circuit
30%
Open ground circuit for fuel heater element
20%
Failed fuel heater relay stuck closed
15%
Faulty PCM unable to pull control circuit low
Diagnostic Steps
1
Step 1: Disconnect fuel heater connector and measure voltage at harness side; should be 0V with key on if PCM-controlled
2
Step 2: Check ground circuit continuity from fuel heater to chassis or PCM ground; should be less than 1 ohm
3
Step 3: Inspect wiring harness for chafing or damage that could cause short to power
4
Step 4: Test fuel heater relay (if equipped) for proper operation and check if it's stuck closed
5
Step 5: Monitor PCM command signal with scan tool while checking actual circuit voltage to verify PCM control
Estimated Repair Cost
$100 - $550
Parts + labor, varies by vehicle and location
The PCM has detected abnormally high voltage in the fuel supply heater control circuit. This indicates a short to power or an open ground circuit that prevents the PCM from properly controlling the fuel heater.
The most common cause of P2689 (Fuel Supply Heater Control Circuit High) is: Wiring shorted to battery voltage in fuel heater circuit
Typical repair costs for P2689 range from $100 to $550, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Fuel heater may run continuously, potentially overheating components or draining battery. Cold weather operation is not affected but electrical system stress may occur. Address to prevent component damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2689 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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