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P0605

Internal Control Module Read Only Memory (ROM) Error

Car Fault Codes Engine computer & electrical

Severity Medium Do not ignore it; it may get worse and cost more.
Can you still drive? With care, short trips only
Who can fix it? Needs a specialist or dealer
Typical repair time 1 hour – 4 hours
Typical cost SAR 200 to 5,000

What it means

Read only memory (ROM) stores the core operating software of the engine computer (ECU). The computer found that the contents of this memory are not valid, either because of corrupted or incomplete programming, or because the memory itself has failed.

Related codes: P0601P0602P0604P0606

Symptoms4

  • Check engine light on.
  • No start, or the engine stalls after starting.
  • Reduced performance or limp mode.
  • No response to the scan tool in some cases.

Possible causes5

  • Previous programming that was corrupted or interrupted before completion.
  • Non-original modification of the computer software.
  • Internal memory failure in the computer.
  • Very low supply voltage while the computer is working.
  • Moisture or excessive heat exposure.

How to diagnose5

  1. Check whether the computer was recently programmed or tuned.
  2. Check the battery, power supply and grounds at the computer.
  3. Read the software version with a scan tool and compare it with the approved version for the vehicle.
  4. Inspect the computer for signs of water or heat.
  5. Have the software reloaded by the dealer or a programming specialist and see if the code returns.

How to fix5

  1. Fix any power or ground problem.
  2. Reprogram the computer with the original approved software.
  3. Return a tuned computer to its original software.
  4. Replace and program the computer if the code returns after programming.
  5. Clear the codes and confirm the code does not return.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is moderate if reprogramming is enough, and reaches the upper end when the engine computer is replaced and programmed.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

How is this different from P0601?

Both point to a problem with the computer memory contents, but P0605 refers to the core program memory. The steps are similar: check power, then reprogram, then replace if needed.

Is reprogramming enough?

Often, if the software was corrupted. If the code returns after correct programming, the memory itself has failed.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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