What Does P0606 Code Mean?

OBD-II Code P0606 is defined as a PCM Processor Fault 

Want does this mean?

The PCM or Power Train Control Module performs many vital functions in a modern vehicle, such as management of the Fuel System, Ignition System, Transmission, Anti-Lock Brake and Traction Control systems. The PCM regularly runs a self-diagnosis function where it performs normal mathmatical calculations, and if the results of these calculations are not as expected, the P0606 code will be set. 


P0606 Symptoms

  • Check Engine Light will illuminate
  • ABS/Traction Control Light may illuminate
  • Vehicle may not perform and/or shift properly
  • Decrease in fuel economy
  • In some cases, there may be performance problems, such as dying when coming to a stop and/or misfire-like symptoms
  • In unusual cases, there are no adverse conditions noticed by the driver

Common Problems That Trigger the P0606 Code

  • Defective PCM (Power Train Control Module)  
  • Defective PCM wiring/connections
  • Defective PCM ground circuit(s)
  • Defective PCM controlled output devices
  • Defective CAN bus communication

Common Misdiagnoses

  • Ignition problems whose root cause is a defective PCM 
  • Fuel Injection problems whose root cause is a defective PCM

Polluting Gases Expelled

  • HCs (Hydrocarbons): Unburned droplets of raw fuel that smell, affect breathing, and contribute to smog
  • CO (Carbon Monoxide): Partially burned fuel that is an odorless and deadly poisonous gas
  • NOX (Oxides of Nitrogen): One of the two ingredients that, when exposed to sunlight, cause smog

P0606 Diagnostic Theory for Shops and Technicians

When the code P0606 is set in the Powertrain Computer, it means that the Powertrain Computer or PCM is failing its own self-check and has found problems with the CPU (central processing unit ). So, in most cases, the processor itself is defective and the PCM needs to replaced and re-programmed.  But, before you replace the PCM, be sure to check for any shorted output devices that may have caused the CPU to fail. 

When diagnosing a P0606 code, it is important to record any other codes and the P0606 freeze frame data. Then one should duplicate the code setting conditions with a test drive. Pay close attention to the engine load, throttle position, RPM, and road speed because a P0606 can be difficult to detect.


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