OBD-II Code Interpreter

ℹ Guidance only — not a substitute for inspection

Enter the trouble codes from your scanner to see what each one means, how urgent it is, and which checks to do first.

Your codes, interpreted

Enter the codes from your scanner to see what they mean.

Purpose

Turns the codes a scanner reads out of your car into plain language: what each one means, how urgent it is, and which checks are worth doing before you spend money. It is for working out what you are dealing with and what to ask a workshop — not for deciding that a car is fine.

Methodology

Each code you enter is looked up in a reviewed table held by this site. Where there is an entry, the tool reports the affected system, a severity band, and an ordered list of checks. Where there is no entry, it says so rather than guessing.

Codes fall into three groups, and the tool keeps them apart:

Standardised codes we have documented. Interpreted in full.
Standardised codes we have not documented yet. Named as such. These are real, defined codes — this tool simply does not carry an entry for them yet, and a workshop scan tool will.
Manufacturer-specific codes. Their meaning is set by the vehicle's maker and differs between makes, so no general interpretation is possible. The tool says which manufacturer source to check and offers nothing further.

Which group a code belongs to is decided from the code itself. The second character of a trouble code distinguishes the standardised set from a manufacturer's own, so the tool can be accurate about what it does not know.

Formula or decision basis

There is no calculation. Severity is a property recorded in the reviewed table against each code; nothing is inferred from the wording of a code at the time you look it up.

When you enter several codes, the result takes the highest severity among them — never an average, and never a count. One stop-driving code alongside nine minor ones produces a stop-driving result. Each code keeps its own severity in the itemised list below the headline.

The checks are the reviewed order for each code, combined and de-duplicated so that two codes sharing a first step do not ask you to do it twice.

Worked example

Entering P0301 P0171 returns:

P0301 — Ignition (service now). Cylinder 1 is misfiring.
P0171 — Fuel and air metering (service soon). Bank 1 is running lean.

The headline takes the higher of the two and reads have this looked at now. The combined checks lead with the flashing-warning-light instruction from the misfire entry, then the coil-and-plug swap, then the vacuum-leak inspection from the lean entry — because a lean condition is a common cause of a misfire, and finding it may resolve both.

Assumptions

A stored code identifies the circuit or system that reported a fault. It does not identify the failed part: a sensor very often reports a problem that something else caused, which is why replacing the part named in a code is such a common and expensive mistake.

The tool assumes the codes you type are the codes your scanner showed. It cannot see your vehicle, its history, its mileage, or anything a code was not stored for.

Limitations

This tool will never tell you a vehicle is safe to drive. The strongest thing it says is that no stop-driving condition was identified from the codes you entered, which is a statement about the codes and not about the car. Faults that store no code, and faults that store a code this tool cannot interpret, are invisible to it.

It covers a reviewed subset of standardised codes rather than all of them, and it covers no manufacturer-specific codes at all.

It is not a substitute for a physical inspection, and nothing here is a repair instruction. If you smell fuel, see smoke, hear a new noise, or the warning light is flashing rather than steady, stop and get the vehicle looked at regardless of what any code says.

FAQ

Does a stored code mean I need the part it names?

No, and this is the most expensive misunderstanding in home diagnosis. A code names the circuit that reported a fault. An oxygen sensor code very often means the sensor is correctly reporting a problem somewhere else — an exhaust leak, or a vacuum leak upstream.

The light went off by itself. Is the fault fixed?

Not necessarily. Many faults have to be absent for several drive cycles before the light clears, and an intermittent fault will clear and return. The stored code usually remains readable after the light goes out.

Should I clear the code before going to a workshop?

No. Clearing it erases the freeze-frame data recorded when the fault occurred, which is often the most useful thing a workshop has to work with.

Why will this tool not tell me whether I can drive?

Because it cannot know. It sees a few characters you typed, not the vehicle. Telling you a car was safe on that basis would be a guess presented as a fact, and the consequences of being wrong sit with you rather than with us.