P0121 - Throttle/Pedal Position Sensor/Switch A Range/Performance

TPS/APP signal is outside expected range.

Treat the code as the starting point: compare symptoms, likely causes, and repair paths before pricing parts or moving into an estimate.

Code Overview

TPS/APP signal is outside expected range.

Common Causes

• TPS/APP sensor drift
• Throttle body sticking
• Wiring issue

Diagnostic Steps

1. Check live data for dropouts
2. Inspect throttle plate for carbon
3. Verify connector pins tight

Likely Repairs & Cost Guides

Use symptoms, scan data, and quick checks to confirm the likely repair path before pricing parts. The estimator helps compare repair paths before replacing anything unnecessarily.

Related OBD Codes

Browse nearby code-family pages when the same fault pattern overlaps across systems, such as misfire, lean fuel trim, EVAP sealing, cooling, or charging faults.

Next Steps

Move from code lookup to diagnosis, then estimate the likely repair only after symptoms, causes, and checks point to the same path.