P0221: Throttle/Pedal Position Sensor B Circuit Range/Performance
The P0221 code indicates that the Engine Control Module (ECM) has detected a signal from the throttle position sensor (TPS) or accelerator pedal position sensor (APP) 'B' that is out of the expected range or not performing correctly. This sensor is typically part of a dual or redundant sensor system used to monitor throttle plate angle or pedal position. The ECM compares the signals from sensor A and sensor B; if they do not match within a specified range, or if the B signal is erratic or stuck, the code sets. Common causes include a faulty sensor, wiring issues, or a misadjusted throttle stop.
1. Most Common Causes
- Faulty or worn throttle position sensor (TPS) or accelerator pedal position sensor
- Loose or corroded connections in the sensor harness
- Short circuit, open circuit, or high resistance in the TPS 'B' circuit wiring
- Carbon buildup or dirt in the electronic throttle body restricting throttle plate movement
- Mechanical failure in the throttle body (e.g., damaged spring or gears)
- Reference voltage (VREF) from the ECM out of specification
- Failed engine control module (ECM) – rare
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode activated
- Poor acceleration or hesitation
- Erratic idle or stalling
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for additional codes.
Step 2: Visually inspect the TPS/APP sensor connector and wiring for damage or corrosion.
Step 3: With a multimeter, test the sensor's reference voltage (typically 5V) and ground, then check the signal voltage while slowly opening the throttle (should vary smoothly).
Step 4: Compare sensor A and B signals; if they do not correlate, replace the sensor.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. The vehicle may enter limp mode, limiting speed and acceleration, which can be dangerous in traffic. Have it diagnosed promptly.
How much does it cost to fix?▼
Typically $50-$150 for parts and labor, but costs can vary if the throttle body assembly needs replacement or if there is extensive wiring repair.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.