P0220 OBD2 Code Guide
P0220 is a powertrain diagnostic trouble code. Use this hub to understand the plain meaning, the first checks to run, and which vehicle-specific guides may be more useful before replacing parts.
Throttle/Pedal Position Sensor/Switch B Circuit Malfunction
Code P0220 signifies that the Powertrain Control Module (PCM) has detected an electrical circuit malfunction within the Throttle Position Sensor (TPS) or Accelerator Pedal Position Sensor (APPS) "B" circuit. Modern vehicles employ multiple redundant sensors (typically two or three) for both the throttle body and the accelerator pedal to ensure precise and safe throttle control. Sensor "B" is one of these critical inputs, providing a signal to the PCM that is compared against other sensors (like sensor "A"). A "circuit malfunction" can mean a range of issues, including an open circuit, a short to ground, a short to voltage, or an out-of-range signal that doesn't correlate correctly with other sensor inputs. This code often triggers the "limp home" mode, severely limiting engine power to prevent unintended acceleration or other dangerous conditions.
Code verification standard
P0220 is published with SAE J2012 / ISO 15031-6 code structure plus OBD2 P0220 diagnostic context.
First checks
- - Read all stored and pending codes before clearing anything.
- - Save freeze-frame data so you know speed, load and temperature when the code set.
- - Inspect wiring, connectors, fuses, hoses and obvious leaks tied to the named system.
- - Compare live data against realistic values before buying sensors or modules.
- - Clear the code only after repair and complete a drive cycle to confirm it does not return.
P0220 diagnostic path
- 1Visual Inspection and Related Codes: Begin by thoroughly inspecting the wiring harness and connectors leading to the throttle body (for TPS) or accelerator pedal assembly (for APPS). Look for any signs of fraying, corrosion, loose connections, or physical damage. Check for other related diagnostic trouble codes (DTCs) such as P0120, P0221, P0222, P0223, P2135, or P2138, which could indicate a broader issue with the throttle/pedal system.
- 2Scan Tool Live Data Analysis: Connect an OBD-II scan tool and monitor the live data stream for the Throttle Position Sensor (TPS) or Accelerator Pedal Position Sensor (APPS) "A" and "B" voltage readings. With the ignition on and engine off, slowly depress and release the accelerator pedal. Observe if both sensor "A" and "B" voltages increase and decrease smoothly and proportionally, and if they maintain a consistent correlation (e.g., one might be half the voltage of the other, or they might be inverse). A sudden drop, spike, or flatline in sensor "B" voltage, or a significant deviation from sensor "A" without corresponding movement, indicates a problem.
- 3Multimeter Voltage Checks: Disconnect the TPS/APPS sensor "B" connector. Using a digital multimeter, check for proper reference voltage (typically 5V) at the reference wire and a good ground connection at the ground wire. Then, with the sensor reconnected (if possible to back-probe) or by carefully probing the harness, check the signal wire voltage while manipulating the throttle plate or accelerator pedal. Compare these readings to manufacturer specifications. An incorrect reference voltage, poor ground, or erratic signal voltage points to a circuit or sensor issue.
- 4Continuity and Resistance Checks: With the battery disconnected and the PCM connector unplugged (if safe and accessible), perform continuity checks on the signal, reference, and ground wires between the sensor connector and the PCM connector. Look for open circuits or shorts to ground/power. Also, measure the resistance of the sensor itself (if applicable and specified by the manufacturer) to determine if the internal potentiometer is faulty.
Verify before repair
- - Repair or Replace Damaged Wiring/Connectors: Often, the issue is simply a corroded, loose, or damaged wire or connector in the TPS/APPS circuit. Repairing or replacing the affected section can resolve the code.
- - Replace the Throttle Position Sensor (TPS) or Accelerator Pedal Position Sensor (APPS) Assembly: If the sensor itself is faulty (internal potentiometer wear, erratic signal), replacing the entire TPS unit (often integrated into the throttle body) or the APPS assembly is necessary.
- - Clean Throttle Body (for TPS issues): In some cases, a very dirty or sticky throttle plate can prevent the TPS from returning to its correct idle position or moving smoothly, leading to out-of-range signals. Cleaning the throttle body can sometimes resolve this, though it's less common for a "circuit malfunction" code.
- - PCM Reprogramming/Replacement: While rare, a faulty PCM internal circuit or incorrect software calibration could cause this code. A PCM reflash or replacement might be required after exhausting all other diagnostic possibilities.
Vehicle-specific pages to check next
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