Check Engine Light Diagnosis & Repair
A check engine light can mean a loose gas cap or a problem that's about to get expensive. Here's how to tell, and how we find out for sure.
Solid or flashing?
A solid light means the engine computer has detected a fault that affects emissions or performance. It's not usually an emergency, but get it checked soon. Small problems like a vacuum leak or a failing sensor can hurt fuel mileage and lead to bigger ones.
A flashing light usually means an active misfire bad enough to damage the catalytic converter. Reduce speed, avoid heavy acceleration or towing, and get the vehicle looked at as soon as you can.
On diesels, the check engine light often shows up alongside DEF, DPF or "reduced engine power" messages. Don't ignore those; some will limit your speed if left alone.
Common causes
- Loose or faulty gas cap and evaporative system leaks
- Oxygen and air-fuel ratio sensors
- Ignition coils and spark plugs (misfires)
- Vacuum leaks and intake problems
- Mass airflow and throttle position sensors
- Catalytic converter efficiency
- Diesel EGR, DPF, DEF and NOx sensor faults
What we do
We scan the engine computer for stored and pending codes and review freeze-frame data showing what the engine was doing when the fault set. Then we test the circuit or component the code points to, so we know whether the part itself failed or something else, like wiring, a vacuum leak or fuel pressure, is causing it. You get a clear explanation and a price before any repair. If the light turns out to be minor, we'll tell you that too.
Gas and diesel
We diagnose check engine lights on gas cars, SUVs and trucks, and on diesel pickups and vans, including Ford Power Stroke and Ram Cummins. Read more about our diagnostic process.
Very good people, they break down what's going on and why. It makes the world of a different to me. Edit: Very reliable shop had another issue after the throttle positioning sensor went down ( they fixed ) not only did they fix basically my entire rear end rebuilt they did it at a reasonable price.
Check engine light FAQ
Is it safe to drive with the check engine light on?
If it's solid and the vehicle drives normally, it's usually okay to drive to the shop soon. If it's flashing, or the vehicle is running poorly, overheating or losing power, reduce driving and get it checked right away.
Will clearing the code fix the problem?
No. Clearing the code turns the light off temporarily, but if the fault is still there, the light will come back. Finding and fixing the cause is the real fix.