P0605Generic code

P0605 Code: Internal Control Module Read Only Memory (ROM) Error

The P0605 code means the computer found an error in the memory that holds its program (ROM). Check the power supply and grounds before you replace the computer.

Severity
Medium
Can I keep driving?
Yes, but with caution
Estimated cost
$0 to $1,500
Difficulty
Hard
System
Computer and Outputs
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0605 code means

The computer checks at startup that its program is not damaged. If it finds an error, it stores the P0605 code. Sometimes reprogramming fixes it. If it does not, the computer is bad.

Before you decide the computer is bad, always check its power supply and grounds. Low voltage, a loose terminal or a corroded ground cause internal errors that go away once they are corrected. It is also worth looking for software updates from the manufacturer, because many of these codes are resolved by reprogramming the computer without replacing it.

If the computer has to be replaced, keep in mind that it almost always needs programming: VIN, immobilizer, option configuration and, on many vehicles, relearn procedures afterward. A used computer that has not been programmed can leave the vehicle unable to start.

P0605 code symptoms

  • Check engine light on.
  • The engine may not start or may run in limp mode.
  • Other codes at the same time in several systems.

Likely causes of the P0605 code

  1. Computer power supply or ground: low voltage or a connection with resistance.
  2. Battery disconnected or discharged, a cause that matters most for the keep alive memory code P0603.
  3. Software with bugs. Manufacturer updates exist.
  4. Moisture or corrosion inside the computer from deteriorated case seals or water getting in through the engine bay.
  5. Internal failure of the computer. Only after you rule out everything above.

How to diagnose the P0605 code step by step

  1. Clear the code and see whether it comes back. Some are caused by a one-time event, such as a discharged battery.
  2. Measure the voltage at the computer power pins and compare it with the battery.
  3. Measure the voltage drop on the grounds. It should be under 0.1 V with a load.
  4. Look for technical service bulletins and software updates.
  5. Inspect the computer connector for moisture, corrosion or bent pins.

How to fix the P0605 code

  • Correct the power supply and the grounds.
  • Reprogram or update the computer.
  • Replace the computer only if everything above is good, and program it.
  • Clear the codes and verify.

Technical reference data

  • Supply voltage: battery voltage, with less than 0.2 V of drop.
  • Programming needs a stable voltage, so use a battery maintainer.
  • Reference values only: check the manufacturer data for your vehicle.

Brand-specific notes

Manufacturers publish software updates that fix many of these codes. Check with the dealer before you replace the computer.

P0605 on Ford

Software updates have fixed related codes such as P0606 on Ford vehicles.

P0605 on Chrysler

Software updates have fixed related codes such as P0606 on Chrysler vehicles.

P0605 on Hyundai

Software updates have fixed related codes such as P0606 on Hyundai vehicles.

Frequently asked questions about P0605

Can I drive with the P0605 code?
It depends on the symptoms. If the engine runs normally, drive with caution. If it goes into limp mode, take the vehicle to a shop.
Does the computer have to be replaced?
Not always. Many times it is the power supply, a ground or the software.
Does a used computer work?
Only if it is programmed correctly for your vehicle.
How much does it cost to fix P0605?
From $0 (if it was the battery) up to $1,500 if the computer has to be replaced and programmed.
What does the P0605 code mean?
The P0605 code is a generic OBD2 code for a read only memory error. The computer found an error in the memory that contains its program.
Can reprogramming fix a P0605 code?
Sometimes it can, which is why you should ask about a software update first. If the error stays after a clean reprogramming with stable power, the computer itself is bad.

Related codes

Questions about the P0605 code

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