Throttle/Pedal Position Sensor/Switch B Circuit Range/Performance
P0221 indicates the engine control module detected a signal problem with the throttle position sensor (TPS) circuit B, meaning the sensor's voltage reading is outside the expected range or not responding properly. This prevents the engine from accurately detecting throttle input, affecting acceleration and engine idle control.
What You Might Notice
- Check Engine Light illuminated
- Intermittent stumbling during acceleration or deceleration
- Black smoke on hard acceleration
- Engine may not start or starts with difficulty
- Erratic idle or hesitation when pressing accelerator
Most Common Causes
- 1
Throttle Position Sensor Failure
The TPS may have developed an internal short, open circuit, or worn contact causing it to send erratic or out-of-range voltage signals to the PCM.
- 2
Wiring or Connector Issues
The harness may be rubbing and causing an open or short in the circuit, or the connector at the TPS may have a poor connection, corrosion, or water intrusion preventing proper signal transmission.
- 3
Corroded or Damaged Sensor Connector
Water, salt, or corrosion in the TPS connector or sensor pins can degrade the electrical connection and cause intermittent signal problems.
- 4
Faulty PCM or Module
Though less common, the powertrain control module itself may have a defect preventing it from properly reading valid TPS signals.
How to Diagnose It
- 1
Check Throttle Position Sensor Failure — The TPS may have developed an internal short, open circuit, or worn contact causing it to send erratic or out-of-range voltage signals to the PCM.
- 2
Check Wiring or Connector Issues — The harness may be rubbing and causing an open or short in the circuit, or the connector at the TPS may have a poor connection, corrosion, or water intrusion preventing proper signal transmission.
- 3
Check Corroded or Damaged Sensor Connector — Water, salt, or corrosion in the TPS connector or sensor pins can degrade the electrical connection and cause intermittent signal problems.
- 4
Check Faulty PCM or Module — Though less common, the powertrain control module itself may have a defect preventing it from properly reading valid TPS signals.
How to Fix It
- 1
Inspect and Clean TPS Connector
Locate the throttle position sensor connector, disconnect it, and inspect for corrosion, water damage, or loose pins. Clean contacts with electrical contact cleaner and reconnect firmly, then clear the code and test.
- 2
Check Wiring Harness for Damage
Inspect the wiring harness from the TPS to the PCM for pinched, abraded, or exposed wires that could cause shorts or opens. Repair or replace damaged sections of the harness as needed.
- 3
Replace Throttle Position Sensor
If the connector and wiring are intact, the TPS itself is likely faulty and needs replacement. Remove the old sensor from the throttle body and install a new one, then clear the code and verify operation.
- 4
Test and Replace PCM if Necessary
If all wiring, connectors, and the sensor test good but the code persists, the PCM may be faulty. Have the module tested by a specialist or replaced if confirmed defective.
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