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Engine Fault Code P0605

Internal Control Module Read Only Memory (ROM) Error

Care Engine Code Reader
The Engine Fault Code P0605 indicates an `Internal Control Module Read Only Memory (ROM) Error.` This code is related to the engine control module (ECM) or powertrain control module (PCM) in your vehicle. Essentially, it means that the computer in your car is having trouble accessing its internal memory, which can lead to various performance issues.

Here are some common reasons for this code:

1. Faulty ECM/PCM: The control module itself may be defective.
2. Corrupted Software: The software in the ECM might be corrupted and needs to be reprogrammed.
3. Wiring Issues: Damaged or corroded wiring or connectors can interrupt communication.
4. Power Supply Problems: Insufficient voltage or grounding issues can affect the module`s performance.

While P0605 generally has the same meaning across most manufacturers, some vehicles might have specific nuances. Here are a few examples:

Porsche: Similar issues might arise, but the diagnostic tools used may differ.
Mini: The code can indicate software issues specific to the Mini`s unique control systems.
Mercedes: Mercedes vehicles might have additional codes or subcodes related to the P0605, indicating specific components that may be affected.
Audi: Audi may have its own diagnostic procedures that could lead to different interpretations based on the vehicle`s systems.
Jaguar: In Jaguars, this code might also relate to luxury features that require precise control module functions.
Land Rover: Similar to Jaguar, Land Rover may have additional layers of complexity in their systems.

If you encounter this code, it`s best to consult a professional mechanic with experience in your specific vehicle brand for accurate diagnosis and repair.
The Engine Fault Code P0605 indicates an issue with the internal control module`s Read Only Memory (ROM). This code can pop up in various vehicles, including European brands like Porsche, Mini, Mercedes, Audi, Jaguar, and Land Rover. Here are some common causes for this error:

1. Faulty Engine Control Module (ECM): The ECM itself might be damaged or malfunctioning, leading to ROM errors.

2. Corrupted Software: Sometimes, the software in the ECM can get corrupted due to updates or power surges.

3. Wiring Issues: Damaged or frayed wiring harnesses connected to the ECM can cause communication errors.

4. Poor Connections: Loose or corroded connectors can disrupt the signal between the ECM and other components.

5. Voltage Issues: Problems with the vehicle`s electrical system, such as low voltage or spikes, can affect the ECM`s performance.

6. Battery Problems: A weak or failing battery can cause the ECM to lose its memory or function improperly.

7. Faulty Sensors: Sometimes, a malfunctioning sensor can trigger the ECM to throw this code.

8. Environmental Factors: Extreme temperatures or moisture can impact the ECM`s performance.

Manufacturer-Specific Notes:

Porsche: If the error appears in a Porsche, it may also relate to specific software issues that require a factory reset or update.

Mini: In Minis, this code might be linked to the vehicle`s unique communication protocols, so checking the entire network is crucial.

Mercedes: Mercedes vehicles often have complex systems, so a full diagnostic scan may be needed to pinpoint the issue accurately.

Audi: In Audis, the issue could also be related to the vehicle`s MMI or infotainment system affecting the ECM.

Jaguar: Jaguars may have specific ROM updates that need to be applied if this code appears.

Land Rover: For Land Rovers, the P0605 code might be more prevalent in older models, where wiring and connectors are more prone to wear.

If you encounter this code, it`s essential to perform a thorough diagnostic check to determine the exact cause and address it accordingly.
The P0605 code indicates an issue with the internal control module`s read-only memory (ROM). This can happen in various European cars, including Porsche, Mini, Mercedes, Audi, Jaguar, and Land Rover. Heres how to approach fixing it:

General Steps to Fix P0605:

1. Check Battery and Connections:
– Start by inspecting the battery. A weak or failing battery can cause various codes, including P0605. Ensure the battery is fully charged.
– Check all electrical connections to the engine control unit (ECU). Look for loose, corroded, or damaged connectors.

2. Scan for Other Codes:
– Use an OBD-II scanner to check for other trouble codes. Sometimes, P0605 appears with other codes that can help pinpoint the problem.

3. Inspect Wiring:
– Examine the wiring harness connected to the ECU for any signs of damage or shorts. Repair or replace any damaged wires.

4. Reset the Code:
– Clear the code using an OBD-II scanner. After clearing, take the car for a test drive to see if the code returns.

5. Check ECU:
– If the code comes back, the ECU may be faulty. In some cases, a software update may be available from the manufacturer that can fix the issue.

6. Replace ECU:
– If the ECU is confirmed to be faulty, it will need to be replaced. This often requires programming the new ECU to work with your vehicle.

Manufacturer-Specific Considerations:

Porsche:
– Ensure the ECU is compatible with your specific model and year. Some models may have specific programming requirements.

Mini:
– Check for known issues with the ECU on your specific Mini model. Some may have recalls or service bulletins related to the ECU.

Mercedes:
– Mercedes vehicles often have complex systems. If the problem persists, consider taking it to a dealer for a more thorough diagnostic.

Audi:
– Audi may require specialized tools for ECU programming if replacement is needed. Ensure you have access to the right equipment.

Jaguar:
– Jaguars may have specific diagnostic tools. Consider using a Jaguar-specific scanner for better results.

Land Rover:
– Similar to Jaguar, Land Rover vehicles may have unique diagnostic requirements. A dealer may be the best bet for persistent issues.


Fixing a P0605 code involves a systematic approach to diagnosing the issue. Start with simple checks and move to more complex solutions like ECU replacement if needed. Always consult your vehicles service manual or a professional for specific guidance related to your model.
Driving with a P0605 code, which indicates an Internal Control Module Read Only Memory (ROM) error, is generally not safe. This code means theres an issue with the engine control module (ECM) or powertrain control module (PCM) that can affect the vehicle`s performance. Heres a breakdown based on different manufacturers:

General Considerations:
– Engine Performance: You may experience poor engine performance, stalling, or difficulty starting the vehicle.
– Check Engine Light: The check engine light will likely be on, indicating a problem that needs attention.
– Safety Features: Some safety features may be disabled, which could increase the risk of accidents.

Manufacturer-Specific Insights:

1. Porsche:
– P0605 can lead to reduced power and potential overheating. Its best to avoid driving until the issue is resolved.

2. Mini:
– Similar to Porsche, driving with this code can lead to performance issues. Its advisable to have it checked as soon as possible.

3. Mercedes-Benz:
– Mercedes vehicles may go into `limp mode,` limiting speed and power. It`s safer not to drive until the issue is diagnosed and repaired.

4. Audi:
– Audis may experience loss of power and erratic shifting in automatic models. Its best to have it looked at quickly.

5. Jaguar:
– Driving with a P0605 code can lead to engine misfires or stalling. Its recommended to seek repairs promptly.

6. Land Rover:
– Similar issues can occur with Land Rovers, including reduced engine performance. Avoid driving until the problem is fixed.


While you might be able to drive a short distance in some cases, its not recommended. The risks associated with performance issues and potential safety hazards make it wise to address the P0605 code before continuing to drive. Always consult a professional mechanic for a proper diagnosis and repair.

OBD Codes Explained

Engine Codes

P is for PowerTrain - Engine and Transmission.

P0 Indicates Generic Powertrain Codes

P0 Codes indicate problems with the powertrain and are common for all vehicles using the OBD-II Standard.

P1 Enhanced Manufacturer Specific Codes

P1 Codes are specific to manufacturers.

Sub-System

The 3rd Digit indicates the Sub-System

1 – Emission Management

2 – Injector Circuit

3 – Ignition

4 – Emission Control

5 – Vehicle Speed and Idle

6 – Computer and Output

7 – Transmission

8 – Transmission

9 – Reserved

0 – Reserved

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