P0601

Internal Control Module Memory Check Sum Error

Car Fault Codes Engine computer & electrical

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

Each time it starts, the engine computer (ECU) checks the software stored in its memory by calculating a verification number called a checksum. If the number does not match the expected value, it sets this code, meaning the software is corrupted or the memory is faulty, and the engine may run abnormally or not at all.

Symptoms4

Check engine light on.
Hard starting or no start.
Sudden stalling or limp mode with reduced power.
Shifting problems on some vehicles.

Possible causes5

A previous programming session that did not finish or was interrupted.
Non-original modification of the computer software.
Very low battery voltage or unstable power while the computer is working.
Poor ground connections for the computer.
Internal memory failure from moisture, heat or electronic damage.

How to diagnose5

Ask whether the computer was recently programmed or tuned.
Test the battery and charging system and confirm good power and grounds at the computer.
Clear the code and restart; if it returns immediately, the software or memory is at fault.
Inspect the computer and its connectors for water or corrosion.
Have the dealer or a programming specialist check the software version and reload it.

How to fix5

Fix any battery, power supply or ground problem first.
Reprogram the engine computer with the original manufacturer software.
Return a tuned computer to its original software.
Replace and program the engine computer if the error returns after reprogramming.
Clear the codes and confirm the code does not return over several drive cycles.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

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

Reprogramming often solves it at moderate cost; the cost reaches the upper end when the memory is damaged and a new programmed computer is needed.

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

Do I have to replace the engine computer?

Not always. Start with power and ground checks and a reprogram; replacement is needed only if the code returns after a correct reprogram.

Could a performance tune have caused it?

It is a common cause, because modified software or an interrupted flash changes the memory contents so the checksum no longer matches.

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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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