P0600: Serial Communication Link Malfunction
Quick Answer
Not safe to drive
P0600 indicates that the ECU has detected an internal communication error on its serial data bus. This means the various control modules inside your vehicle cannot properly exchange vital information, which can affect engine management, transmission shifting, and several other critical safety systems.
- Severity
- High · Electrical
- Estimated repair cost
- From €40 to €1900+, varies by vehicle
€40 or €1900, depending on your car.
- Battery and ground connection repair€40–€160
- ECU/PCM replacement and programming€550–€1900
A scan shows whether P0600 is really stored on your car, which codes sit next to it and how urgent each one is. You can do this parked, with the ignition on.
A scan needs a Bluetooth OBD2 adapter (Bluetooth LE on iPhone), about €25-60; the built-in demo runs without one. See which adapter to buy
What does P0600 mean?
P0600 is a electrical-related diagnostic trouble code classified as high severity.
What are the symptoms of P0600?
- Check engine light illuminated
- Multiple warning lights on dashboard
- Engine stalling or rough running
- Transmission shifting erratically
- Loss of speedometer or other gauges
- Vehicle may enter limp mode
What causes P0600?
Faulty ECU/PCM (internal processor or memory failure)
: high
Corroded or damaged CAN bus wiring
: medium
Low battery voltage or poor ground connections
: medium
Water intrusion into ECU housing
: low
Failed ECU software update or corrupted firmware
: low
Is it safe to drive with P0600?
No - address this immediately. Internal ECU communication failure can cause unpredictable behaviour including sudden stalling, loss of power steering, or disabled safety systems. Do not drive until diagnosed.
How do you diagnose P0600?
- Check battery voltage with a multimeter. It should read 12.4V or higher with the engine off and 13.5-14.5V while running. Low voltage can cause serial communication errors.
- Inspect all ECU ground points for corrosion or loose connections. Clean and retighten any suspect grounds.
- Scan for additional codes in all modules. A generic OBD2 reader sees only the engine-related modules, so a full check usually needs manufacturer-level software. Multiple communication codes point to a CAN bus wiring issue rather than a single module failure.
- Inspect the CAN bus wiring harness for chafing, corrosion, or rodent damage, particularly around the ECU connector and along the firewall.
- If wiring checks pass, attempt an ECU reset by disconnecting the battery for 15 minutes. If the code returns immediately, the ECU likely needs replacement or reprogramming.
How much does P0600 cost to fix?
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| ECU/PCM replacement and programming | €400–€1500 | €150–€400 | €550–€1900 | Professional |
| CAN bus wiring repair | €20–€100 | €100–€300 | €120–€400 | Professional |
| Battery and ground connection repair | €10–€80 | €30–€80 | €40–€160 | Easy |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
P0600 on specific vehicles
Volkswagen
Volkswagen Golf
2004-2024
Check the scuttle and pollen filter housing drains for blockages, and check the battery, since the engine computer needs a stable supply.
Ford
Ford Focus
2005-2022
A fault on the CAN bus can set P0600, so the connectors and ground points of the wiring are worth checking before a control unit is replaced.
Opel
Opel Astra
2004-2023
A voltage supply fault to the engine control unit can also set P0600, so the battery and the ECU supply are worth checking before a control unit is replaced.
Renault
Renault Megane
2003-2023
Related diagnostic codes
- P0606
- P0601
- P0602
- P0603
- P0604
Common questions about P0600
- What does P0600 mean on my car?
- P0600 means the engine control unit has detected a failure in its internal serial communication link. The modules inside your car use this data bus to share information, and when it fails, multiple systems can malfunction simultaneously.
- Can I drive with a P0600 code?
- It is not recommended. P0600 can cause unpredictable engine behaviour including stalling, and may disable safety-critical systems. Have it diagnosed as soon as possible.
- Can a weak battery cause P0600?
- Yes. Low battery voltage can cause serial communication errors, so always check your battery health and charging system before assuming the ECU is faulty.
- How much does it cost to fix P0600?
- If the issue is a bad ground or low battery, repairs can cost under 100 EUR. If the ECU itself has failed, expect 550-1900 EUR for replacement and programming at a dealership.
- Is P0600 always an ECU failure?
- No. The engine computer itself can be at fault, but wiring problems, poor grounds and low battery voltage can all trigger P0600, and a proper diagnosis rules out these cheaper fixes first.