P0606: Control Module Processor

What does P0606 mean?

P0606 means the module doubts the integrity of its own processor. Checks include a question-and-answer game between main and monitoring processor (GM: new seed via SPI within 450 ms; Ford: 'quizzer' level 3), arithmetic unit and register tests, stack overflow, the order in which safety-critical software runs, and the internal voltage supply (Ford diesel: 5 V rail outside 4.7–5.3 V). Because it belongs to the electronic throttle safety concept, the module usually reacts with a failure mode – reduced power, RPM limit or throttle default position – and the lamp in the first trip. Many cases are software issues fixed by reprogramming (Chrysler 3.6 L 2014, VW Routan, GM brake module 2024), so check bulletins before replacing hardware. The code alone does not say which module set it – the scan tool shows whether it is the engine, transmission, brake or body module.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light, at Ford also the wrench lamp
• Limp mode with reduced power or RPM limit
• Poor throttle response
• Rarely stalling or no start
• Often together with voltage codes P0562/P0563

Common causes

• High Faulty module software (update available)
• Medium Low voltage, voltage dips or a poor ground or supply at the module
• Medium Internal hardware defect (processor, voltage regulator, output stage chip)
• Low Short on a 5 V sensor reference loading the internal supply

Likelihood is a general estimate across vehicles; your make and model may differ.