Introduction:

The B1220 diagnostic trouble code (DTC) signifies a "Fuel Tank Pressure Sensor Circuit Open." This indicates an issue with the electrical circuit connected to the fuel tank pressure (FTP) sensor. This sensor is crucial for monitoring the pressure within the fuel tank, a vital component of the vehicle's evaporative emission (EVAP) control system. An open circuit disrupts the signal from the FTP sensor to the engine control unit (ECU), potentially leading to various drivability problems and emissions failures.

Comprehensive Table: B1220 Fuel Tank Pressure Sensor Circuit Open

Aspect Description Potential Causes Symptoms

Detailed Explanations:

1. B1220 Code Definition:

The B1220 code specifically indicates that the ECU has detected an open circuit in the fuel tank pressure sensor circuit. This means that the electrical connection between the sensor and the ECU is broken, preventing the ECU from receiving the correct signal from the sensor. This can occur at various points within the wiring harness, connectors, or even the sensor itself.

2. Fuel Tank Pressure Sensor Function:

The Fuel Tank Pressure (FTP) sensor monitors the pressure inside the fuel tank. This information is critical for the EVAP system to function correctly. The EVAP system captures fuel vapors to prevent them from escaping into the atmosphere. The FTP sensor helps the ECU determine when to purge these vapors into the engine to be burned during normal combustion, thus reducing emissions.

3. Potential Causes:

  • Damaged Wiring: This is a very common cause. Wires can become frayed, corroded, or broken due to age, exposure to the elements, or physical damage. Look for signs of wear and tear, especially near connectors and points where the harness is routed along the chassis.
  • Loose or Corroded Connectors: The connectors at the FTP sensor and the ECU can become loose, corroded, or damaged. Corrosion increases resistance and can eventually break the electrical connection.
  • Faulty FTP Sensor: The sensor itself could be defective. Internal components can fail, leading to an open circuit.
  • ECU Issue: While less common, a problem within the ECU could cause the B1220 code. This is usually only considered after ruling out other possibilities.
  • Rodent Damage: Rodents often chew on wiring harnesses, causing damage and broken connections. This is especially common in vehicles that are stored for long periods or parked in areas with rodent activity.
  • Aftermarket Accessories: Improperly installed aftermarket accessories, such as alarms or remote starters, can sometimes interfere with the FTP sensor circuit.
  • Improper Repairs: Previous repairs to the wiring harness or EVAP system could have been done incorrectly, leading to an open circuit.
  • Extreme Temperatures: While less common, extreme temperatures can sometimes affect the integrity of wiring and connectors, leading to failures.

4. Symptoms:

  • Check Engine Light (CEL): This is the most common and obvious symptom. The ECU detects the fault and illuminates the CEL.
  • EVAP System Problems: The EVAP system may not function correctly, leading to potential fuel vapor leaks and emissions failures.
  • Difficulty Starting: In some cases, a faulty FTP sensor can affect the engine's ability to start, although this is less common with an "open circuit" code.
  • Poor Fuel Economy: If the EVAP system is not functioning properly, it can affect fuel economy.
  • Fuel Odor: You might notice a fuel odor, especially after fueling or when the vehicle is parked. This indicates potential fuel vapor leaks.
  • Failed Emissions Test: The vehicle will likely fail an emissions test due to the EVAP system malfunction.
  • Rough Idling: The engine might idle roughly or stall, although this is less common with an open circuit specifically.
  • Hesitation During Acceleration: In rare cases, the engine might hesitate during acceleration due to the EVAP system malfunction.

Troubleshooting Steps:

  1. Visual Inspection:
    • Thoroughly inspect the wiring harness and connectors associated with the FTP sensor. Look for any signs of damage, corrosion, or loose connections. Pay close attention to the wiring near the sensor and the ECU.
  2. Check the FTP Sensor Connector:
    • Disconnect the connector from the FTP sensor and inspect the pins for corrosion or damage.
    • Use a multimeter to check for voltage at the connector with the ignition on. You should typically see a reference voltage (often 5 volts).
  3. Wiring Harness Continuity Test:
    • Use a multimeter to check the continuity of the wires in the FTP sensor circuit. Disconnect the connector from both the FTP sensor and the ECU.
    • Check for continuity between the corresponding pins on the sensor connector and the ECU connector. A lack of continuity indicates an open circuit.
  4. Wiring Harness Short to Ground Test:
    • With the connectors disconnected, use a multimeter to check for a short to ground in the FTP sensor circuit.
    • Measure the resistance between each wire in the circuit and ground. A low resistance reading indicates a short to ground.
  5. Inspect the FTP Sensor:
    • If the wiring and connectors appear to be in good condition, the FTP sensor itself may be faulty.
    • Consider replacing the FTP sensor with a new one.
  6. Check the ECU:
    • As a last resort, if all other components check out okay, the ECU might be the problem. However, ECU failures are relatively rare.
    • Consult a qualified technician to diagnose and repair the ECU.
  7. Use a Scan Tool:
    • A scan tool can provide valuable information about the FTP sensor readings and other EVAP system parameters.
    • Monitor the FTP sensor data to see if it is within the expected range.

Tools Required:

  • Multimeter
  • Wiring diagram for your specific vehicle
  • Scan tool (optional, but helpful)
  • Wire strippers/crimpers
  • Connectors and wiring (if repairs are needed)

Frequently Asked Questions:

  • What does the B1220 code mean? It means the engine control unit (ECU) has detected an open circuit in the fuel tank pressure sensor circuit.

  • Can I drive with a B1220 code? Yes, but it's not recommended. The EVAP system won't function correctly, leading to potential emissions issues and reduced fuel economy.

  • Is the B1220 code serious? It can be, as it affects the EVAP system and can cause emissions failures. Prompt repair is recommended.

  • How do I fix a B1220 code? Troubleshoot the wiring, connectors, and FTP sensor. Repair or replace any damaged components.

  • Can a loose gas cap cause a B1220 code? No, a loose gas cap usually triggers a different code related to EVAP leaks, not an open circuit.

  • How much does it cost to fix a B1220 code? The cost varies depending on the cause. A simple wiring repair might be inexpensive, while replacing the FTP sensor or ECU will be more costly.

  • Where is the fuel tank pressure sensor located? The location varies by vehicle, but it's typically found near the fuel tank or on top of the fuel pump assembly. Check your vehicle's repair manual for the exact location.

Conclusion:

The B1220 Fuel Tank Pressure Sensor Circuit Open code indicates a break in the electrical circuit to the FTP sensor, preventing proper EVAP system operation. Thoroughly inspect the wiring, connectors, and sensor itself, and repair or replace any faulty components to resolve the issue and ensure optimal vehicle performance and emissions compliance.