Is it safe to drive with this code?

Ordinary braking typically remains functional, but traction control and stability systems may be disabled or operating improperly. Driving in dry conditions at moderate speeds may be acceptable in the short term, but you should avoid slippery roads, heavy rain, or snow until the fault is addressed, and our site disclaimer applies—always use your own judgement and prioritise safety.

C0004 itself does not automatically cause an MOT failure; what matters is whether the malfunction indicator lamp (MIL) for ABS or traction control is illuminated at the moment of test. If the lamp remains on during the test, that may result in a fail—see our full disclaimer for details.

Roughly how much does it cost to fix?

Repair costs vary widely depending on the root cause. A straightforward wiring repair or connector replacement may fall into the low three-figure range (£100–£300), while a faulty valve solenoid replacement and labour can reach the mid three-figure band (£300–£700). If the ABS/TCS control module requires replacement or reprogramming, costs may climb into the high three-figure to four-figure range (£700+), particularly at main dealers. Independent specialists often charge less for labour than franchised workshops.

Can I clear the code and ignore it?

Clearing the code without repairing the underlying fault will typically result in the code returning once the ECU performs its next self-check. Traction control and stability systems are important safety features, especially in adverse weather, so addressing the root cause is advisable rather than simply resetting the warning.

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← All fault codes | ABS / ESP

C0004

Chassis

Traction Control System (TCS) Control Channel "A" Valve 1 (Subfault)

The traction control system has detected a fault in one of the hydraulic valves that manages brake pressure to help maintain grip on slippery surfaces.

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ⓘ Information only. This page provides general educational information about fault code C0004. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.

Recommended next steps

Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.

What does C0004 mean?

C0004 is a Chassis (ABS, traction control, steering) fault code. It indicates: Traction Control System (TCS) Control Channel "A" Valve 1 (Subfault).

This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.

About ABS / ESP codes

Codes in this category relate to the anti-lock braking system (ABS) and electronic stability control (ESP/ESC). These systems share wheel speed sensors, hydraulic modulators, and a common control module. Faults here usually disable ABS pulse braking and stability control assistance, but standard hydraulic brakes continue working normally.

C0004 is one of 429 codes in this category. Browse all ABS / ESP codes →

What we know about C0004 specifically

We record the SAE J2012 standardised definition and the system this code belongs to, but we have not yet published detailed driver-reported symptoms, common causes, or step-by-step diagnostic guidance for C0004.

Rather than invent that information by generating generic content from a template, we leave it out. For specific guidance, the most reliable sources are:

•your vehicle's own service manual or manufacturer-specific technical bulletins
•a qualified mechanic with a manufacturer-level diagnostic tool
•a marque specialist familiar with your make and model

Codes nearby

Codes adjacent to C0004 in the C-code series. Many fault codes appear together with their neighbours because they relate to the same circuit or component.

C0001 Traction Control System (TCS) Control Channel "A" Valve 1 (Subfault)

C0002 Traction Control System (TCS) Control Channel "A" Valve 1 (Subfault)

C0003 Traction Control System (TCS) Control Channel "A" Valve 1 (Subfault)

C0020 ABS Pump Motor Relay Control Circuit/Open

C0021 Left Front Wheel Speed Sensor Circuit

C0022 Right Front Wheel Speed Sensor Circuit

Other ABS / ESP codes

Other fault codes in the same system as C0004. The ones with detailed guides have plain-English explanations, symptoms, causes, and diagnostic steps.

B1106

Shift Lock Circuit Failure Detailed guide

C0021

Left Front Wheel Speed Sensor Circuit Detailed guide

C0035

Left Front Wheel Speed Sensor Circuit Range/Performance Detailed guide

C1000

Abnormality in Stoplight Switch Circuit Detailed guide

C1602

Manufacturer-Specific Chassis/ABS Fault Detailed guide

B1082

ORC-Occupant Restraint Control-Fps-Fire Protection Strategy-Activated

Spotted an issue or have something to add? Mechanics, technicians, and drivers who have first-hand experience with C0004 can submit a correction or expansion. We review every submission before publishing, mechanic submissions are prioritised.

Information only, not professional advice

The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →

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