The check engine light (also called the malfunction indicator lamp) comes on when your vehicle’s onboard computer detects a problem it can’t correct on its own — usually something affecting the engine, transmission, or emissions system. It stores a trouble code that points a technician toward the system involved. The light itself doesn’t tell you how urgent the problem is; that depends on what triggered it and whether the light is steady or flashing.
Steady vs. Flashing
A steady check engine light usually means the fault isn’t an emergency, but it should be checked soon — a small problem left alone often becomes a larger one.
A flashing check engine light is different. It typically means an active engine misfire that can quickly damage the catalytic converter, which is an expensive part. If your light is flashing, ease off the throttle, avoid hard acceleration, and get the vehicle looked at right away. More detail here: flashing vs. steady check engine light.
Common Causes
- A loose or failed gas cap — a real cause, not just a myth; it sets an evaporative-emissions leak code
- Worn spark plugs or ignition coils causing a misfire
- A failing oxygen sensor or mass airflow sensor
- Catalytic converter problems
- EVAP system leaks — purge valve, vent valve, or a cracked hose
- A vacuum leak
- Less often, a transmission or other sensor fault
Is It Safe to Drive?
If the light is steady and the car drives normally — no unusual noises, no loss of power, no overheating, no strange smells — it’s usually fine to drive a short distance to get it checked.
If the light is flashing, or the car is running rough, losing power, or overheating, stop driving it and call for advice.
Why a Code Read Isn’t a Diagnosis
A free code read at a parts store tells you which system set a code — for example, a cylinder-misfire code. It doesn’t tell you why. That same code can come from a spark plug, an ignition coil, a fuel injector, a vacuum leak, low compression, or a wiring problem.
A proper diagnosis is the testing that isolates the actual cause before you spend money on parts.
Serving Albuquerque's North Valley
We’re at 4201 4th St NW in the North Valley, an easy stop for drivers from Los Duranes, Griegos, Wells Park, and the Sawmill District, as well as Rio Rancho and Corrales. See our check engine light diagnosis for how we track down the cause.
Frequently Asked Questions
Will the check engine light turn off by itself? Sometimes. If the fault stops happening, the light can go out after several drive cycles, but the trouble code usually stays stored and the problem often returns. Having it read while it’s recent makes the diagnosis easier.
Can I pass emissions with the light on? No. In Bernalillo County a lit check engine light is an automatic failure regardless of the tailpipe readings. The cause has to be repaired and the readiness monitors reset before the vehicle will pass.
How much does a diagnosis cost? There’s a charge for diagnostic time because it’s hands-on testing, not just plugging in a scanner. We tell you the fee up front and go over what we found and what the repair involves before any work begins.