P2125 OBD-II Trouble Code: Throttle/Pedal Position Sensor/Switch "E" Circuit

P2125 code definition

P2125 is a general OBD-II trouble code indicating a fault with the throttle/pedal position sensor/switch “E” circuit. This code is similar to many other throttle body and pedal position codes.

What the P2125 code means

The engine control module (ECM) uses the signals from the throttle body and position sensor to command the throttle body actuator motor to open the throttle plate. This allows air into the engine and is varied by how hard the pedal is pressed and how far.

This code will only be seen on cars with a drive-by-wire or an electronically controlled throttle body. Once the ECM detects a fault with the sensor or switch circuit “E” the P2125 code is set, and this causes a Check Engine Light to be displayed on the dashboard. With the Check Engine Light, the ECM puts the vehicle into a failsafe mode to prevent any further damage to the vehicle.

What causes the P2125 code?

Many different components can cause the P2125 code:

• Open or short in the wiring harness
• Failed throttle actuator control motor
• Throttle position sensor that has failed
• Failed pedal position sensor
• Poor electrical connection

What are the symptoms of the P2125 code?

Symptoms can sometimes be felt before the Check Engine Light is displayed on the dashboard. A wide range of symptoms are seen with the P2125 code such as:

• Check Engine Light illuminated on the dash
• The vehicle may not move when the gas pedal is depressed
• Engine may exhibit a misfire condition
• Vehicle may run poorly

How does a mechanic diagnose the P2125 code?

Mechanics will follow these simple steps when performing diagnosis of the P2125 code:

• Using a scan tool to check the ECM for any stored codes including history and pending codes

• Noting all codes that are present as well as the freeze frame data associated with each code

• Clearing all codes for a clean slate

• Performing a test drive of the vehicle attempting to duplicate the conditions found in the freeze frame data

• Conducting a visual inspection to look for any damaged components, worn or broken wires, and broken parts

• Using the scan tool and its datastream to watch the sensor “E” while the throttle and gas pedal are operated. There should be changes in the values if they are working properly.

• Finally, a multimeter will be used to check that voltage is present at the sensor and for continuity

Common mistakes when diagnosing the P2125 code

Mistakes can be made with any code if steps are not followed in the proper order or skipped entirely. Overlooking simple steps can lead to the wrong components being replaced which wastes both time and money.

How serious is the P2125 code?

P2125 can have some rather serious symptoms. If the ECM can’t detect the signal from the throttle/pedal switch, it may not allow the throttle to work at all. If this occurs, the vehicle will not move at all when the gas pedal is depressed. If drivability problems are present, the vehicle should not be driven and should be repaired as soon as possible.

What repairs can fix the P2125 code?

The most common repairs of the P2125 code are:

• Failed throttle actuator control motor replaced
• Repaired or replaced wiring harness
• Replacement of the throttle position sensor
• Resolving the electrical connection issues

Additional comments for consideration regarding the P2125 code

An advanced-level scan tool goes a long way towards helping diagnose the P2125 code. These tools give technicians access to advanced features in the ECM with the most helpful being the ECM’s live data stream. This tool shows sensor and solenoid data, and allows the mechanic to monitor operation and note changes over time.

Need help with a P2125 code?

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