OBD2Verified

P0122

Throttle Position Sensor/Switch A Circuit Low

beginnerEst. 30-60 minutes

This diagnostic information is provided for agricultural, off-road, and competition use. Repair procedures may not be appropriate for on-road emissions-controlled vehicles. Consult a certified technician for on-road repairs.

Overview

The ECM has detected that the throttle position sensor (TPS) signal voltage is below the expected range. This typically indicates a faulty TPS, damaged wiring, or a poor electrical connection in the throttle body circuit.

Symptoms

Rough or unstable idle

Poor acceleration and hesitation

Engine stalling at idle or during deceleration

Check Engine Light (MIL) illuminated

Vehicle may enter limp/reduced power mode

Erratic or jumpy RPM readings

Common Causes

01Faulty Throttle Position Sensor (TPS)

02Corroded or damaged TPS connector pins

03Open or shorted wiring in TPS circuit

04Poor ground connection at TPS

05Damaged throttle body

06Failed ECM/PCM (rare)

Golden Values

Verified Measurements

The Examiner's Golden Values5 measurements

Parameter	Range	Typical	Notes
Reference Voltage Tool: Multimeter	4.8–5.2 V	5 V	Key on, engine off — measured at TPS connector pin C
Signal Voltage (Closed Throttle) Tool: Multimeter	0.4–0.8 V	0.5 V	Key on, engine off — throttle fully closed
Signal Voltage (WOT) Tool: Multimeter	4–4.8 V	4.5 V	Key on — throttle fully open manually
Ground Continuity Tool: Multimeter	0–5 Ω	1 Ω	TPS ground pin to chassis ground
TPS Sweep Test Tool: Multimeter or Oscilloscope	0.4–4.8 V	—	Smooth linear increase from closed to WOT — no dropouts or jumps

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