P2108 – Throttle Actuator Control Module Performance

What is Code P2108?

OBD-II diagnostic trouble code (DTC) P2108 stands for "Throttle Actuator Control Module Performance". This code indicates that the powertrain control module (PCM) has detected a malfunction with the throttle actuator control system.

Urgency and Severity

When code P2108 is triggered, it is generally not an urgent issue that requires immediately stopping the vehicle. In most cases, you can continue driving cautiously to a repair shop. However, engine performance may be reduced and the vehicle may enter a "limp home" mode with limited power. If drivability is severely impacted, it's best to have the vehicle towed to avoid a safety risk.

General vs. Manufacturer-Specific

P2108 is a generic powertrain code that applies to all makes and models of vehicles equipped with OBD-II, including Chevy, Ford, Toyota, Honda, etc. The specific troubleshooting procedures may vary slightly between manufacturers.

Parts Involved

The main components related to code P2108 are:

• Throttle Body: Controls the amount of air entering the engine. Contains the throttle plate and throttle actuator.
• Throttle Actuator: An electric motor that opens and closes the throttle plate based on signals from the PCM.
• Throttle Position Sensor (TPS): Measures the opening angle of the throttle plate and sends this information to the PCM.
• Accelerator Pedal Position Sensor (APPS): Detects the position of the gas pedal pressed by the driver.

Common Causes

Potential causes of a P2108 code include:

1. Faulty throttle actuator motor
2. Dirty or sticking throttle body
3. Damaged throttle position sensor
4. Faulty accelerator pedal position sensor
5. Wiring issues such as damaged wires, loose connections, or corrosion
6. Faulty PCM (rare)

Diagnosis Steps

1. Connect an OBD-II scan tool and check for any other codes. Address those first if present.
2. Visually inspect the throttle body for carbon buildup or obstructions. Clean if necessary.
3. Check the wiring harness and connectors for damage. Repair as needed.
4. Using a multimeter, test the throttle actuator motor and sensors for proper operation.
5. If no issues are found, suspect a faulty PCM.

Repair Solutions

• Clean the throttle body and plate
• Replace a faulty throttle actuator motor
• Replace a damaged TPS or APPS
• Repair damaged wiring or connectors
• Replace the PCM if faulty

Prevention

• Regularly clean the throttle body every 50,000-100,000 km (30,000-60,000 miles)
• Address any running issues promptly to prevent carbon buildup
• Avoid aftermarket "performance chips" that alter throttle mapping

Repair Cost

The cost to diagnose and repair a P2108 code can range from $100-$600 (€85-€510) depending on the root cause:

• Throttle body cleaning: $100-$200 (€85-€170)
• Throttle body replacement: $300-$600 (€255-€510)
• Throttle/pedal sensor: $100-$300 each (€85-€255)
• Wiring repairs: $100-$300 (€85-€255)

Related Codes

Other codes commonly seen with P2108 include:

• P2135 – Throttle/Pedal Position Sensor/Switch A / B Voltage Correlation
• P2138 – Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation
• P0121 – Throttle Position Sensor/Switch A Circuit Range/Performance Problem
• P0221 – Throttle/Pedal Position Sensor/Switch B Circuit Range/Performance Problem

In summary, code P2108 indicates a throttle actuator system performance issue that should be diagnosed promptly to restore proper drivability, but does not typically require immediate stoppage of the vehicle. Cleaning the throttle body and checking the actuator motor and sensors is the best starting point for troubleshooting.

Frequently Asked Questions About P2108

What does the OBD-II code P2108 mean?

P2108 is a generic powertrain code that indicates the powertrain control module (PCM) has detected a malfunction with the throttle actuator control system, specifically related to the control module’s performance.

What are the common symptoms of code P2108?

Symptoms may include reduced engine performance, limited throttle response, engine entering “limp home” mode, illuminated check engine light, possible engine stalling, or failure to start.

Is it safe to drive with a P2108 code?

While the vehicle may still be drivable, it’s best to diagnose and repair the issue promptly to avoid further damage and restore proper performance. If drivability is severely impacted, have the vehicle towed to a repair shop.

What are the potential causes of a P2108 code?

Potential causes include a faulty throttle actuator motor, dirty or sticking throttle body, damaged throttle position sensor (TPS) or accelerator pedal position sensor (APPS), wiring issues, or rarely a faulty PCM.

How do you diagnose a P2108 code?

Diagnosis steps include scanning for other codes, visually inspecting the throttle body and wiring, testing the actuator motor and sensors with a multimeter, and suspecting the PCM if no other issues are found.

What parts are involved with a P2108 code?

The main components are the throttle body, throttle actuator motor, throttle position sensor, and accelerator pedal position sensor.

Can a dirty throttle body cause code P2108?

Yes, a dirty or sticking throttle body can prevent the throttle plate from moving properly, triggering the code.

How do you repair a P2108 code?

Repairs may involve cleaning the throttle body, replacing a faulty actuator motor, TPS, or APPS, repairing damaged wiring, or replacing the PCM if faulty.

How much does it cost to fix code P2108?

The cost can range from $100-$600 depending on the root cause. Throttle body cleaning is $100-$200, sensor replacement $100-$300 each, and a new throttle body $300-$600.

Can you clean the throttle body yourself?

Yes, the throttle body can be cleaned with throttle body cleaner and a soft brush. Remove the air intake boot, spray cleaner inside the throttle body, scrub gently, let soak, then wipe clean.

How often should the throttle body be cleaned?

Cleaning the throttle body every 50,000-100,000 km (30,000-60,000 miles) or as needed can help prevent buildup that may cause issues.

Can a weak battery cause a P2108 code?

Unlikely. While a weak battery can cause issues with sensor readings, it would more likely trigger a voltage-related code than P2108 specifically.

Can a vacuum leak cause code P2108?

Indirectly, yes. A vacuum leak can allow unmetered air into the engine, confusing the sensors and PCM which may cause the throttle actuator to behave unexpectedly.

What is a throttle actuator motor?

The throttle actuator motor is an electric motor located in the throttle body that opens and closes the throttle plate, controlling air flow into the engine. It is controlled by the PCM.

What does “limp home mode” mean?

Limp home mode is a safety feature where the PCM detects a major malfunction and limits engine performance to allow the vehicle to be driven to a repair shop, though speed and power are greatly reduced.

Can a faulty throttle position sensor cause a P2108?

Yes, the TPS tells the PCM the exact position of the throttle plate. If it sends an implausible signal, the PCM may log a P2108.

What other codes may be present with P2108?

Related codes can include P2135 and P2138 (TPS/APPS correlation), P0121 and P0221 (TPS circuit range/performance), among others.

Can a software update fix code P2108?

Unlikely, as P2108 typically indicates a hardware issue with the throttle actuator system. A software update would more commonly fix codes related to programming or communication issues.

How do you test a throttle actuator motor?

With the ignition off, disconnect the throttle body electrical connector. Using a multimeter set to ohms, measure the resistance between the motor power and ground pins. Specification vary, but it’s typically 2-25 ohms.

What happens if you unplug the throttle position sensor?

Disconnecting the TPS will likely trigger a fault code and put the vehicle into limp home mode, as the PCM will not know the position of the throttle plate. The engine may stall or fail to start.