Error Code P1515 is defined as Control Module Throttle Actuator Position Performance.

This error code is a manufacturer-specific trouble code, meaning it does not apply to all vehicles makes. Rather, it applies only to specific vehicle makes, such as BMW, GM, etc. Specification on the definition, troubleshooting, and repairs still vary from one make and model to another.


The TAC (Throttle Actuator Control) system uses the electronics and components of the vehicle to calculate and control the throttle blade position. This eliminates the need for a mechanical cable attachment that would run from the accelerator pedal to the throttle body. This system also provides cruise control functions.

The components of the TAC system include, but are not limited to:

  • The APP (Accelerator pedal position) sensors
  • Throttle body
  • PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes)

Each of these components interfaces together, making sure the system gets the most accurate calculations and control of the TP (throttle position).

Throttle Body Assembly

The throttle body assembly for the TAC system is very similar to the conventional throttle body, but with some exceptions. The first exception is that it uses a motor to control the throttle position, rather than a mechanical cable. Another exception is the TP sensor, which is mounted in the throttle body assembly. There are two separate signals, low reference and a 5V reference circuit used to connect the TP sensors and the PCM. TP sensor 2 signal voltage increases as the throttle body opens. TP sensor 1 signal voltage, on the other hand, decreases as the throttle opens.

Common Symptoms

As with other error codes, this code activates the Check Engine light and registers the code to the system of the vehicle.

Possible Causes

Error Code P1515 is usually caused by:

  • Poor TAC module connection
  • Defective TAC
  • Defective TPP (Throttle Pedal Position) or TPS (Throttle Position Sensors)
  • Bend or binding throttle plate-failed throttle body

How to Check

In many cases, outdated PCM can cause this problem. Thus, you need to check your PCM if it’s updated.

Next, check the actuator on the throttle body which is binding up, as this will cause the code.

Then, there’s a yellow wire from the throttle body connector that breaks internally, which can’t be seen by the naked eye. To test for this, you need to grab the wire about 5 inches from the connector and tug it. If it feels spongy or if it breaks, then there’s the problem.

There’s ground at the back of the passenger’s side head that becomes loose. Check it.

How to Fix

Update the PCM. If that doesn’t correct the problem, you may need to replace the throttle body unit and connector to it. Check the ground on the back of the head.

Also, check the wires in the throttle body connector, look for breakage and unhook it. Spray electrical cleaner and apply dielectric grease on both male and female end of the connector.

Also, check for grounds to the ECBM and other grounds. Clean and sand them.

Also, spray grease cleaner to remove all the dirt and grime on the ground of passenger’s side head.

In many cases, updating the PCM will fix this code.