Fault code P2129 – throttle/pedal position sensor/switch “E” circuit intermittent/erratic

Fault code P2129 is called “Throttle/Pedal Position Sensor/Switch (TPS) “E” Circuit Intermittent/Erratic” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P2129

This Diagnostic Trouble Code (DTC) is a general powertrain code. Error P2129 is considered a general code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly from model to model.

The throttle position sensor (TPS) reacts to the movement of the accelerator pedal. It is a type of potentiometer. It converts the throttle position into a voltage output and sends a voltage signal to the engine control module (ECM). It also determines the opening and closing speed of the throttle and provides a voltage signal to the ECM.

Code P2129 means that the computer detects a certain amount of intermittent or erratic signals from the TPS (Throttle Position Sensor “E”). Within a set period of time and under a programmed set of circumstances.

When the throttle is closed, the signal is about 0.45 volts and the lower limit when open is 0.17 to 0.20 volts.

Simply put, the throttle position sensor is used to determine what position the throttle is in. If the signal value is intermittently lost (intermittent) due to a bad contact, this code is set.

Symptoms of vehicle malfunctions

The main signal that an error P2129 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

1. Check engine light on the control panel will illuminate.
2. Ignition jerking/missing at idle or under load.
3. Engine stalls or starts poorly.
4. The engine cannot be accelerated, throttle response is unresponsive.
5. Poor acceleration.
6. Increased fuel consumption.
7. Engine power decrease due to slow throttle response.

If fault P2129 occurs, the engine may run at higher idle speeds, but the vehicle will not accelerate properly. It is recommended to eliminate the fault code as soon as possible to avoid aggravating the problem.

Factors that can cause this error code

The error code P2129 can mean that one or more of the following problems have occurred:

• Throttle position sensor circuit is open or bad electrical connection.
• Throttle position sensor wiring harness is open or shorted to ground or other wire.
• Corrosion on MAP or TPS connector.
• Throttle position sensor is defective.
• Throttle valve return spring is stuck.
• Engine control module (ECM) is defective.

How to fix or reset OBD-2 code P2129

Some suggested steps for troubleshooting and fix the error code P2129:

1. Read all stored data and error codes with an OBD-II scan tool. To find out when and under what circumstances the error occurred.
2. Clear the error codes from the computer memory and test-drive the vehicle to find out if the malfunction appears again.
3. Visually inspect the electrical wiring and connections related to the throttle “E” position sensor for looseness and damage.
4. Compare “A” and “E” throttle position sensor readings using a scan tool, replace faulty sensor if necessary.
5. Check for proper operation of the return spring.
6. Clear error code from computer memory again, test drive vehicle to see if problem is resolved.

Diagnose and repair of problems

Carefully check the throttle position sensor (TPS), wiring connector, and wiring itself for breaks, etc. Repair or replace if necessary to clear error P2129.

Check the voltage on the TPS, it should be between 0.45-0.17 volts (some vehicles may have different values). If the voltage is too low or too high, this indicates a problem. Replace the sensor if necessary.

If recently replaced, you may need to adjust the TPS. On some vehicles, the installation instructions require a proper adjustment (see repair manual for details).

If there are no symptoms, the problem may be intermittent, and clearing the code may temporarily resolve it. If this is the case, you should definitely check the wiring to make sure it is not chafing or frayed anywhere, etc.

On which vehicles does this problem occur most frequently

Fault code P2129 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

• Audi
• Chevrolet (Lacetti)
• Chrysler
• Dodge
• Ford (Focus)
• Hyundai (Solaris)
• Jeep
• Kia (Rio)
• Mazda
• Nissan
• Peugeot

Fault code P2129 can sometimes be found with other errors. The most common are the following: P2125, P2126, P2127, P2128.

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