Who to hire when the check engine light comes on

Short answer

A licensed mechanic. How urgent depends on the behaviour: a steady light with the car driving normally usually means get it looked at soon, while a flashing light generally means stop driving, because in most vehicles it indicates a misfire that can destroy the catalytic converter within minutes.

Soon, not tonightIt will not usually get cheaper by waiting, and it is rarely worth an after-hours rate.

What to do before anyone arrives

  1. Note whether the light is steady or flashing, and whether anything else changed — power, noise, smell, temperature, fuel economy.
  2. Check the fuel cap is on properly and clicks. A loose cap genuinely triggers an evaporative-system code and it is the cheapest possible cause.
  3. Note when it came on and under what conditions. Cold start, after refuelling, under load uphill — all useful.
  4. If you have a code reader or a scan app, read the code and write it down. It does not tell you the fix but it tells the mechanic where to start.

What to ask when you book

  • What is the diagnostic charge, and is it credited against the repair?
  • What code is stored, and what does it actually indicate on this vehicle?
  • Are you replacing a part because the code names it, or because you have tested it? Codes name the circuit, not always the faulty component.
  • Is this safe to drive in the meantime?

What changes the price

No dollar figures here: this directory holds no price data and an invented range is worse than none. What follows is what makes one of these jobs cost more than the same job next door, which is the part you can actually use when comparing quotes.

  • Diagnostic time, which is real work and should be charged as such.
  • Whether the fault is present continuously or intermittently.
  • Parts, and whether the repair requires dealer-level equipment or software.

What you can do yourself

Is this licensed work?

Motor vehicle repair is licensed in every state, with a checkable register. Diagnostic work in particular is where the difference between workshops shows.

There is no national register. Search the licence number with the regulator for the state the work is happening in.

Licensing thresholds and certificate requirements differ by state and change with amending regulation, so this page describes the mechanism rather than quoting a figure. The regulator’s own page is the current answer.

Common questions

Who should I hire when the check engine light comes on
A licensed mechanic. How urgent depends on the behaviour: a steady light with the car driving normally usually means get it looked at soon, while a flashing light generally means stop driving, because in most vehicles it indicates a misfire that can destroy the catalytic converter within minutes.
Can I keep driving with the check engine light on?
A steady light with no change in how the car drives usually means it can be driven to a workshop, and should be, soon. A flashing light generally means an active misfire, which sends unburnt fuel into the exhaust and can destroy the catalytic converter quickly — that one means stop.
Why does the light come back after a repair?
Either the underlying fault was not fixed, or the code was cleared before the repair was verified, or the fault is one that only sets again after a specific drive cycle. A workshop that clears a code and hands the car back without verifying the repair under the conditions that set it has not finished the job.

Find a Mechanic near you

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Who to hire for

General information about who does what, not advice about your specific job. Licensing, consumer law and council rules differ by state and change; the regulator for your state is the current source. More guides to hiring a tradesperson.