7,726 fault codes explained
Decode your dashboard.
Warning light on? Enter your fault code for a plain-English explanation of what it means. Information only. Always confirm any diagnosis with a qualified mechanic.
7,700+ codes
OBD and manufacturer-specific in one library
Plain English
no jargon, what it means and what to do
Categorised
Powertrain, Chassis, Body or Network, at a glance
Free to use
no login, no subscription, no small print
How it works
Three steps from warning light to a more informed conversation with a mechanic.
1. Read the code
Plug a reader into the OBD-II port under the dashboard, usually within reach of the steering wheel on the driver's side. You'll get something like P0300 or C0021.
2. Look it up here
Type it into the search box above. No jargon, just what it means and which system it belongs to.
3. Talk to a mechanic, informed
Every code page covers symptoms, likely causes and the steps a mechanic would actually take. Read it first and the conversation in the garage goes a lot better. Always get a proper diagnosis before deciding anything.
Browse by system
Find codes by the part of the car they relate to.
Most-searched fault codes
The codes UK drivers and mechanics look up most. Each has a full plain-English guide.
Common questions
What is an OBD fault code?
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OBD stands for On-Board Diagnostics. Your car's computer constantly monitors hundreds of sensors. When something goes wrong, it stores a code (like P0300) in memory and usually triggers a warning light. A code reader plugged into your car's OBD port retrieves these codes.
Can I drive with a fault code active?
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Whether a vehicle is safe to drive depends entirely on the underlying cause, which only an in-person diagnosis can confirm. Codes are typically grouped into severity tiers. Many minor B-codes and P4xx emissions codes are commonly considered lower urgency. Moderate codes generally warrant prompt diagnosis. Critical codes (such as oil pressure, coolant, or chassis C0xxx codes) are typically considered urgent. Always confirm with a qualified mechanic before deciding whether to continue driving.
Will clearing the code fix the problem?
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Clearing a code removes the warning light but does not fix the underlying fault. The code will typically return once the car's systems re-test, usually within a few drive cycles. Generally, addressing the underlying cause first is more reliable than clearing the code in isolation.
My code isn't in your database, what does that mean?
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Some very new codes, proprietary manufacturer codes, or codes from specialist equipment may not be in our library. If you can't find your code, try searching by keyword or check with a garage who can run a full manufacturer-level diagnostic.
How do I read fault codes without a code reader?
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You can't without some form of diagnostic tool. Basic OBD-II readers start from around £15 online and plug into the diagnostic port usually found under the dashboard on the driver's side. Many garages and fast-fit centres will read codes for free.
Who runs carfaultcodes.co.uk?
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New Reg Limited, a UK company with over twenty years in the automotive industry.
Found your code? Here's what to do next.
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