P0605 OBD-II Trouble Code: Internal Control Module ROM Error

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P0605 is a diagnostic trouble code (DTC) for "Internal Control Module ROM Error". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $114.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

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P0605 code definition

Internal Control Module ROM Error (Module Identification Defined by SAE J1979)

What the P0605 code means

The Engine Control Module (ECM) is responsible for many major vehicle functions such as ignition timing, anti lock-braking, fuel injection, traction control, electronic power steering (most new makes of vehicles have this) cooling fan operation and emission controls. It is also responsible for smaller tasks such as window operation, radio, and even the horn.

ROM stands for Read Only Memory. The memory consists of parameters the Engine Control Module stores inside of a processor that can not be erased. The Parameters include tests and numeric ranges that the ECM permanently stores for use every time the vehicle is operated in any way. The parameters are several guidelines of how the processor should interpret the codes, and values being sent to it from things including, but not limited to oxygen sensors, mass air flow (MAF) sensors, interior buttons, crank position sensors, and other forms of engine management.

If the information sent to the Engine Control Module does not match the values that are stored in the processor by the manufacturer, a Check Engine Light will occur. There is a possibility that the memory stored in the ECM has been lost or disrupted if a code P0605 occurs.

What causes the P0605 code?

  • Defective or interrupted Engine Control Module ground or power supply
  • Broken Solder point(s) on the circuit board(s) of the ECM from heat or vibrations
  • Loss of memory in the ECM
  • ECM needs to be updated or re-flashed

What are the symptoms of the P0605 code?

  • A Check Engine Light being set
  • Engine misfire
  • Possibly a no start condition
  • Engine stall or hesitation

How does a mechanic diagnose the P0605 code?

  • Checks the related Technical Service Bulletins (TSB’s) and recalls to determine if the Engine Control Module may need an update, flash, or reprogramming

  • Inspects the wires connecting to the ECM

  • Inspects the electrical terminals connecting to the ECM

  • Tests the ECM for proper ground points and power supplies

Common mistakes when diagnosing the P0605 code?

  • Failing to research whether there is a TSB or recall related to updating, flashing, or reprogramming the Engine Control Module

  • Deeming the ECM as bad without verifying that the power supply and grounds to the ECM are good

How serious is the P0605 code?

It is fairly serious and should be addressed immediately. Think of it like this: The Engine Control Module is essentially the mind of a vehicle. Much the same to the operations of a human brain. They both run off of electricity. Similar to how a brain will control functions of a body such as heart rate, breathing rate and motor skills.

The vehicle itself can be compared to the body of oneself. If a brain undergoes any error, there may be a loss in bodily functions. If the ECM has an error, there may be a loss in sufficient control of vehicle functions: the heart rate, (which is, indirectly, ignition timing,) breathing rate, (which is, indirectly, the amount of air a car will suck in through its intake in accordance to the driver demands,) and motor skills. In this case, motor skills can be used as a literal term because a motor is an engine, and the skills are what the ECM uses to control the motor.

What repairs can fix the P0605 code?

  • Repairing a faulty ground or power supply such as corroded components and damaged wiring

  • An Engine Control Module update, reprogramming or reflash (if applicable)

  • Replacing the ECM

Additional comments for consideration regarding the P0605 code

A new Engine Control Module must be programmed to the vehicle. Oftentimes, a reprogramming can only be done with specialty equipment that is commonly only available to the dealership, though some sources other than the dealership may have that equipment. I suggest that you ask the potential installer of the ECM if they have the necessary specialty equipment in order to complete the job.

Need help with a P0605 code?

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Related questions

Multiple error codes.

Those codes are mostly for the transmission control module. I would have a technician come out and test fuses and check voltages and look for a shorted wire. It will probably be a 20 amp fuse for the ECM. (https://www.yourmechanic.com/services/ecm-power-relay-replacement)...

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Hello, thank you for writing in. Lets take a look at these codes separately at first. The P0605 codes stands for a malfunction with the main computer's (PCM-power train control module) ROM (or "Read Only Memory"). The P2105 is then...

Whats wrong , engine codes p0605,p0842,p0642, and p0401 thrown twice , light front end damage wothout airbag deployment

Hello, thank you for writing in. If the vehicle was in a wreck, the issues are likely independent from each other. One issue seems to be a powertrain control module electrical malfunction. This could be an issue with an input...

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