Fault code P1606 – a step-by-step guide to diagnosing and fixing it

Error code P1606 is displayed and the check engine light is on - what does this mean?

The OBD/EOBD system has detected an error in the engine control unit or the electronic accelerator pedal position. This DTC P1606 is a manufacturer-specific trouble code that mainly occurs on General Motors, Chevrolet and other GM vehicles and indicates problems with the electronic throttle control module or communication between control units.

What can cause this error code?

• Defective electronic throttle control module (TAC)
• Damaged cable connections to the accelerator pedal position sensor
• Loose or corroded plug connections on the throttle body
• Faulty engine control unit software
• Defective accelerator pedal position sensor
• Interrupted CAN bus communication between control units
• Voltage problems in the 5V reference voltage
• Mechanical damage to the throttle body

What symptoms occur in parallel with fault code P1606?

• Starting problems: The vehicle cannot be started or starts poorly
• Idling problems: Unsteady or fluctuating idling
• Accelerator pedal response: Delayed or no response to accelerator pedal operation
• Emergency running program: Engine only runs in emergency running mode with reduced power
• Engine stalling: Engine stalls while driving or when stationary
• Acceleration problems: Poor acceleration or jerky engine running

How can I fix the problem with fault code P1606?

• Repairing this fault code requires a systematic diagnosis of the electronic throttle valve control.
• Checking and cleaning all plug connections on the throttle body and accelerator pedal module, followed by a test drive to check function
• Replacement of the electronic throttle control module (TAC) and subsequent reprogramming with the manufacturer's software
• Replacing the accelerator pedal position sensor and carrying out a basic setting via the diagnostic unit
• Updating the engine control unit software to the latest version at an authorized dealer
• Replacing the complete throttle body in the event of mechanical defects and subsequent calibration
• Repair or replacement of damaged wiring harnesses between the affected control units with subsequent function test