What Does B1223 Mean?
B1223 indicates the Body Control Module (BCM) or Powertrain Control Module (PCM) has detected an open circuit condition in the fuel temperature sensor #1 circuit. This sensor monitors the temperature of fuel in the tank or fuel rail to allow for proper fuel density compensation and emissions control. An open circuit means there is a break in the electrical pathway, preventing the control module from receiving any signal from the sensor.
Common Causes
35%
Broken or corroded wiring harness connections at the fuel tank sender unit or fuel pump module connector
30%
Failed fuel temperature sensor internally open or damaged
25%
Damaged wiring between sensor and control module due to chafing, rodent damage, or corrosion
10%
Failed control module (BCM or PCM) with internal circuit failure
Diagnostic Steps
1
Step 1: Perform a visual inspection of the fuel temperature sensor connector at the fuel tank or fuel pump module. Check for corrosion, pushed-out pins, moisture intrusion, or damaged terminals. Wiggle test the connector while monitoring live data for intermittent readings.
2
Step 2: Using a digital multimeter, backprobe the fuel temperature sensor connector and measure resistance across the sensor terminals (sensor disconnected). Compare readings to manufacturer specifications (typically 2000-3000 ohms at 68°F). An infinite resistance reading confirms internal sensor failure.
3
Step 3: Test circuit continuity from the sensor connector back to the control module connector using a multimeter. Check both signal and ground wires for opens. Measure resistance to ground on signal wire with everything disconnected (should be infinite/open circuit, not grounded).
4
Step 4: If wiring and sensor test good, inspect the control module connector for corrosion or damage. Check for supply voltage at the sensor connector (typically 5V reference) with key on, engine off. If no reference voltage is present, suspect control module failure.
5
Step 5: After repairs, clear the code and perform a complete drive cycle. Monitor live fuel temperature data to verify the sensor is providing reasonable values that change with ambient and operating temperatures.
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
B1223 indicates the Body Control Module (BCM) or Powertrain Control Module (PCM) has detected an open circuit condition in the fuel temperature sensor #1 circuit. This sensor monitors the temperature of fuel in the tank or fuel rail to allow for proper fuel density compensation and emissions control...
The most common cause of B1223 (Fuel Temperature Sensor #1 Circuit Open) is: Broken or corroded wiring harness connections at the fuel tank sender unit or fuel pump module connector
Typical repair costs for B1223 range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive as this is primarily used for fuel density compensation and emissions calculations. The vehicle may experience slightly reduced fuel economy or minor driveability issues in extreme temperature conditions, but repair can be scheduled at convenience.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1223 to identify the root cause.
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Quick Info
Category
Body
System
Fuel System / Body Control
Difficulty
Type
Manufacturer
Recommended Tools
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