OBD-II Fault Code

P1121: Throttle Position (TP) Sensor Circuit Intermittent High Voltage

Meaning, symptoms, likely causes, diagnostic checks and repair guidance for P1121.

System family

Powertrain

Manufacturer-specific

Repair category

Throttle / pedal sensor

Use this category to narrow your checks before replacing parts.

Severity

High

Severity is a general guide. Confirm with scan-tool data and vehicle symptoms.

What P1121 usually means

Throttle Position (TP) Sensor Circuit Intermittent High Voltage.

Common symptoms

Check Engine light; Poor drivability or reduced fuel economy depending on fault; Reduced power / limp mode possible; Hesitation or unstable idle

Likely causes

Dirty throttle body; Faulty throttle/pedal position sensor; Wiring/connector fault; Adaptation needed; High signal voltage; Open ground; Short to voltage; Failed sensor; Loose connector; Moisture/corrosion; Harness vibration fault

Diagnostic checks

Scan all modules and record freeze-frame data before clearing codes; Check battery voltage and related fuses; Inspect throttle body and connector; Check sensor correlation data with scan tool; Check sensor ground and signal circuit for short to voltage; Wiggle-test harness while watching live data; Inspect for water intrusion/corrosion

Repair guidance

Clean throttle body if appropriate, repair wiring, perform throttle relearn, replace failed sensor/body after testing; Repair ground/signal circuit or replace confirmed faulty sensor; Clean/secure connector and repair damaged harness

Verification after repair

Clear code, road-test through the same drive condition, then rescan

Note: Confirm vehicle make/model/year because manufacturer-specific codes can vary; Manufacturer-specific: confirm definition and test steps in the vehicle service manual. A DTC identifies a circuit or system condition, not always the failed part.