OBD2 codes

Look up any check engine code.

Find what an OBD2 code means, how serious it is, whether you can keep driving, the most likely causes ranked by frequency, and a real repair-cost range — scoped to your exact year, make, and model.

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How to read an OBD2 code with MECH AI

What is an OBD2 code?

An OBD2 code — also called a DTC (Diagnostic Trouble Code) — is a five-character code your car’s computer stores when it detects a fault. The first letter is the system (P = powertrain, B = body, C = chassis, U = network) and the digits identify the specific problem. For example, P0420 means the catalytic converter is below its efficiency threshold. A code tells you where to look — confirming the actual cause still takes diagnosis.

Most common codes

The check engine codes drivers look up most.

All OBD2 codes

50 powertrain trouble codes, each with a vehicle-specific diagnosis. Pick a code, then choose your year, make, and model.

OBD2 code FAQ

What is an OBD2 code?

An OBD2 code (also called a DTC, or Diagnostic Trouble Code) is a five-character code your car's computer stores when it detects a fault — for example, P0420 means the catalytic converter is below its efficiency threshold. The letter shows the system (P = powertrain, B = body, C = chassis, U = network) and the digits narrow down the specific fault. A code tells you where to look; confirming the actual cause still takes diagnosis.

How do I read an OBD2 code?

Plug an OBD2 scanner into the port under the dashboard (usually below the steering column), turn the key to "on," and read the stored code. The MECH AI iOS and Android app can do this directly — pair a Bluetooth LE (BLE) or WiFi ELM327 adapter and it reads stored, pending, and permanent codes free, with plain-English descriptions (read-only). No scanner at all? The free OBD-II decoder lets you type a code you already have and get its meaning, severity, and likely causes for your exact vehicle.

Is it safe to drive with a check engine light on?

It depends on the code. A steady check engine light usually means you can drive short-term but should diagnose it soon; a flashing light means stop driving — it typically signals an active misfire that can destroy the catalytic converter. Each code page below gives a drive-safety answer for your specific vehicle.

Does clearing a code fix the problem?

No. Clearing a code only turns the light off — if the underlying fault is still present, the code returns once the car re-runs the relevant monitor. Diagnose and repair the root cause first; clear the code afterward to confirm the fix held.

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