Throttle Position (TP) Sensor 1 Circuit
What it means
This is a Chevrolet (GM) manufacturer-specific code, and the same number can mean something different on other makes. Electronic throttle systems use two sensors to measure throttle opening, and this code means the voltage of sensor 1 is outside the accepted limits or its circuit is open or shorted. The engine usually goes into reduced power mode for safety.
Models covered: Chevrolet (GM) models with electronic throttle control, mainly around 1997–2006.
Symptoms4
- A reduced engine power message or light.
- Weak response to the accelerator or limited speed.
- High or unstable idle in some cases.
- Check engine light on, sometimes with other throttle codes.
Possible causes5
- Corrosion or moisture in the throttle body connector.
- An open or short in the sensor 1 wires between the throttle body and the computer.
- A failed TP sensor 1, which is built into the throttle body on most of these systems.
- A short on the shared 5-volt reference circuit used by other sensors.
- A fault in the throttle actuator control (TAC) module or engine computer (rare).
How to diagnose5
- Read stored codes and note whether pedal sensor codes are also present, which points to a shared reference circuit.
- Watch sensor 1 voltage on a scan tool while slowly pressing the pedal, looking for jumps or dropouts.
- Inspect the connector for corrosion or loose terminals.
- Measure reference, ground and signal at the connector and compare with the manufacturer specification.
- Gently move the wiring while monitoring to find an intermittent break.
How to fix5
- Clean and secure the connector or replace damaged terminals.
- Repair the broken or shorted wire.
- Replace the complete throttle body if the built-in sensor is confirmed faulty.
- Perform the throttle position relearn if the manufacturer requires it after replacement.
- Clear the codes, road test and confirm the code does not return.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
The cost is low for a connector or wire, and much higher if a new electronic throttle body is needed, since the sensor is usually not sold separately.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
Why did the vehicle go into reduced power?
The computer no longer trusts one of the two throttle sensors, so it limits throttle opening to avoid unintended acceleration.
Can the sensor be replaced alone?
On most electronic throttle bodies in these models the sensor is built in, so the fix is a complete throttle body once the wiring is confirmed good.
What are the generic equivalents?
Newer models set generic codes such as P0122 or P0123 for low or high voltage in the first sensor circuit.
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What was wrong? (optional)
This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.
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