U0606: Lost Communication With Throttle/Pedal Position Sensor/Switch A

What it means

The vehicle bus reports loss of communication with smart throttle/pedal position sensor A. The ECM loses one of the redundant pedal channels and reverts to a fail-safe pedal map.

At a glance

• Usually lights the warning light of the system that lost communication
• Affects emissions; the car can fail an emissions test
• The engine or gearbox may go into limp mode

How it works

Throttle or pedal position sensor/switch A sends one of the driver-demand signals over the vehicle network. U0606 sets when the engine controller loses communication with channel A, which can compromise the redundant pedal input and trigger limited-throttle fail-safe operation.

Common causes

Most likely first.

1. Bus wiring open or shorted
2. Module without power or ground
3. Module failed

Symptoms

• Multiple warning lights may illuminate
• Affected modules may go into limp mode or shut down
• Specific functions inoperative depending on module
• Diagnostic tools may show communication faults

How to diagnose it

1. Save freeze-frame data and scan all modules for accelerator, throttle, and network codes before clearing anything.
2. Check whether the accelerator response is limited or inconsistent and whether live data for pedal/throttle channel A is missing or implausible.
3. With the vehicle parked, inspect sensor A’s connector and wiring for looseness, corrosion, water intrusion, chafing, or damage near the pedal or throttle body.
4. Compare channel A with the other redundant pedal or throttle channel in live data while slowly operating the pedal, following the vehicle’s service information.
5. Test sensor A’s specified power, ground, and network circuit to the manufacturer’s specification; if these are sound, test the sensor and controller configuration.

Common fixes

• Repair a loose, corroded, wet, or damaged sensor A connector or harness.
• Restore the sensor’s specified power or ground connection.
• Repair network wiring if other devices on the same bus also lose communication.
• Replace throttle or pedal position sensor/switch A if testing confirms it has failed.
• Correct a configuration or controller fault only if vehicle-specific tests identify it.

Can I keep driving?

Avoid driving if throttle response is limited, erratic, or the engine will not respond predictably; arrange safe recovery if needed. Loss of channel A can cause sudden power limitation or unreliable acceleration, making merging and passing unsafe.