What Does B1229 Mean?
This code indicates that the Body Control Module (BCM) or Powertrain Control Module (PCM) has detected an abnormally low voltage on the fuel temperature sensor #2 circuit, indicating a short to ground condition. The fuel temperature sensor monitors fuel temperature to allow the engine control system to compensate for fuel density variations. The control module detected a voltage reading below the acceptable threshold, typically near 0 volts instead of the expected reference voltage range.
Common Causes
45%
Damaged wiring harness or chafed insulation causing the signal wire to contact ground or vehicle chassis
30%
Failed fuel temperature sensor with internal short to ground
15%
Corroded or damaged connector pins at sensor or control module allowing moisture intrusion and ground fault
10%
Control module internal fault causing false short to ground detection
Diagnostic Steps
1
Step 1: Perform a visual inspection of the fuel temperature sensor #2 wiring harness from the sensor to the control module, checking for obvious damage, chafing, pinch points, or exposed wires contacting metal surfaces
2
Step 2: Disconnect the fuel temperature sensor #2 connector and use a digital multimeter to measure resistance between the signal pin on the sensor side and ground. A reading near 0 ohms confirms a shorted sensor; readings of several thousand ohms indicate the sensor is likely good
3
Step 3: With the sensor still disconnected, measure resistance between the signal wire pin on the harness side and ground. A reading near 0 ohms indicates a short in the wiring harness; infinite resistance indicates the harness is intact
4
Step 4: Inspect both the sensor connector and harness connector for corrosion, bent pins, moisture, or contamination. Clean with electrical contact cleaner and ensure proper sealing
5
Step 5: If all wiring and connections test good, replace the fuel temperature sensor #2 and retest. Clear codes and monitor for recurrence
6
Step 6: If the code returns after sensor replacement with confirmed good wiring, suspect a control module fault and perform manufacturer-specific control module diagnostics or consider replacement
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
This code indicates that the Body Control Module (BCM) or Powertrain Control Module (PCM) has detected an abnormally low voltage on the fuel temperature sensor #2 circuit, indicating a short to ground condition. The fuel temperature sensor monitors fuel temperature to allow the engine control system...
The most common cause of B1229 (Fuel Temperature Sensor #2 Circuit Short to Ground) is: Damaged wiring harness or chafed insulation causing the signal wire to contact ground or vehicle chassis
Typical repair costs for B1229 range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle is generally safe to drive with this code as it primarily affects fuel system monitoring and minor fuel trim adjustments. You may experience slightly reduced fuel economy or minor drivability issues in extreme temperature conditions, but continued operation poses no immediate safety risk.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1229 to identify the root cause.
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Quick Info
Category
Body
System
Fuel System
Difficulty
Type
Manufacturer
Recommended Tools
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