P1220 - Throttle Position (TP) Sensor 2 Circuit

Introduction

The P1220 diagnostic trouble code (DTC) indicates a problem with the Throttle Position (TP) Sensor 2 circuit. This sensor is crucial for the engine control unit (ECU) to accurately determine the throttle valve's position. When the ECU detects an anomaly in the TP sensor 2 circuit's signal, it triggers the P1220 code, potentially affecting engine performance, fuel efficiency, and overall drivability. Addressing this issue promptly is vital for maintaining optimal vehicle operation.

Comprehensive Table: P1220 Diagnostic Trouble Code

Detailed Explanations

Definition: The P1220 code signals that the engine control unit (ECU) has detected a malfunction within the circuit connected to Throttle Position (TP) Sensor 2. This sensor is responsible for relaying the throttle valve's position to the ECU, allowing it to manage fuel delivery and ignition timing accordingly. A fault in the circuit disrupts this communication, leading to the error code.

Symptoms: The presence of a P1220 code can manifest in various noticeable symptoms. These often include a reduction in engine power, making acceleration sluggish. The engine might exhibit erratic idling, stalling unexpectedly, or hesitating when accelerating. The check engine light will illuminate, alerting the driver to the issue. In some vehicles, transmission shifting problems and even limp mode engagement can occur.

Possible Causes (Detailed):

• Open Wiring: An open circuit refers to a break in the wiring that prevents the electrical signal from flowing correctly from the TP sensor 2 to the ECU. This break can be caused by damaged or corroded wiring, rodent damage to the harness, or physical stress on the wiring harness.
• Shorted Wiring: A short circuit occurs when a wire comes into contact with another wire or a grounded surface, creating an unintended pathway for the electrical current. This can lead to inaccurate or nonexistent signals from the TP sensor 2. Common causes include wires rubbing together, insulation damage exposing the wires, or wires grounding out against the vehicle's chassis.
• Faulty TP Sensor 2: The sensor itself can be the source of the problem. Internal wear and tear, internal sensor damage, or contamination from external elements can cause the sensor to provide incorrect readings to the ECU.
• Poor Connection: A loose or corroded connection at the TP sensor 2 connector can disrupt the signal flow. Vibration, exposure to moisture, or physical damage to the connector can lead to a poor connection.
• Damaged ECU: While less common, the ECU itself can be faulty, preventing it from properly processing the TP sensor 2 signal. This can be caused by internal ECU failure, water damage, or electrical surges.
• Throttle Body Issues: Carbon build-up or damage to the throttle body can obstruct the free movement of the throttle plate. This, in turn, affects the TP sensor readings, as the sensor is linked to the throttle plate's position. Lack of regular maintenance, poor air filtration, and excessive oil consumption can contribute to throttle body issues.
• Incorrect Adjustment: If the throttle body has been improperly adjusted, it can lead to inaccurate TP sensor readings. This can occur after previous repairs or if someone has tampered with the throttle body settings.
• VREF Problems: The TP sensor requires a stable 5V reference voltage (VREF) to operate correctly. Problems with this voltage supply can cause inaccurate readings. This can be caused by a faulty ECU regulator or a short circuit in the VREF circuit.

Diagnostic Steps:

1. Visual Inspection: Begin by visually inspecting the wiring and connectors associated with the TP sensor 2. Look for any signs of damage, corrosion, or loose connections.
2. Resistance and Voltage Check: Use a multimeter to check the resistance and voltage of the TP sensor 2. Compare your readings to the manufacturer's specifications.
3. Signal Testing: Employ a scan tool (OBD2 scanner) to monitor the TP sensor 2 signal while the throttle is moved. This will help you identify any erratic or inconsistent readings.
4. Throttle Body Inspection: Carefully inspect the throttle body for carbon build-up or any signs of damage that could impede the throttle plate's movement.
5. Reference Voltage Check: Verify that the TP sensor 2 is receiving the correct reference voltage (typically 5V).
6. ECU Testing: As a last resort, consider testing the ECU to rule out any internal issues. This step often requires specialized equipment and expertise.

Tools Required: To effectively diagnose and address the P1220 code, you'll need a few essential tools. These include a multimeter for electrical testing, a scan tool (OBD2 scanner) for reading sensor data, wiring diagrams for your specific vehicle, diagnostic software for advanced analysis, throttle body cleaner for addressing carbon build-up, and basic hand tools for disassembly and reassembly.

Common Mistakes: A common mistake is replacing the TP sensor 2 without conducting a thorough diagnosis. Other errors include overlooking wiring issues, neglecting to check the throttle body's condition, and failing to verify the reference voltage.

Related Codes: Several other diagnostic codes can be related to the P1220 code, including P0120 (Throttle Position Sensor/Switch A Circuit Malfunction), P0121 (Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem), P0122 (Throttle/Pedal Position Sensor/Switch A Circuit Low Input), P0123 (Throttle/Pedal Position Sensor/Switch A Circuit High Input), and P1221 (Throttle Position Sensor 2 Intermittent).

Severity: The severity of the P1220 code is generally considered moderate to high. It can significantly impact drivability and fuel economy. If left unaddressed, it may potentially lead to further engine damage.

Repair Costs: Repair costs can vary widely depending on the underlying cause of the P1220 code. TP sensor replacement typically ranges from $100 to $300. Wiring repairs can cost between $50 and $200. Throttle body cleaning usually falls in the $50 to $150 range. ECU replacement, which is rare, can be a more substantial expense, potentially costing between $500 and $1500 or more.

Frequently Asked Questions

• What does the P1220 code mean? The P1220 code signifies a malfunction in the Throttle Position (TP) Sensor 2 circuit, indicating that the ECU isn't receiving accurate throttle position data. This can affect engine performance.

• Can I drive with a P1220 code? While you can drive, it's not recommended. The code indicates a problem affecting engine performance, potentially leading to stalling, poor acceleration, and reduced fuel economy.

• Is the TP sensor easy to replace? Replacing the TP sensor is generally a straightforward process, but proper diagnosis is crucial. Replacing it without identifying the underlying problem might not resolve the issue.

• How do I test the TP sensor? You can test the TP sensor using a multimeter to check resistance and voltage, and a scan tool to monitor the signal while moving the throttle. Compare readings to specifications.

• Will cleaning the throttle body fix the P1220 code? If carbon build-up in the throttle body is causing the problem, cleaning it might resolve the P1220 code. However, other issues like wiring problems or a faulty sensor could also be the cause.

Conclusion

The P1220 diagnostic trouble code signals a problem within the Throttle Position (TP) Sensor 2 circuit, impacting engine performance and drivability. Thorough diagnosis, including visual inspection, electrical testing, and throttle body assessment, is crucial for accurate repair and restoring optimal vehicle operation.