The check engine light signals a potential engine or emissions problem. The maintenance required light is a reminder to complete routine service.
Both lights appear on the dashboard to prompt different actions: diagnosing faults versus performing scheduled maintenance. Here’s how they differ and what to do when each lights up.
What the Check Engine Light Indicates
The check engine light (CEL), also called the malfunction indicator lamp (MIL), comes on when the vehicle’s computer detects a problem that could affect engine performance or emissions. A diagnostic trouble code is stored, which a technician retrieves with an OBD‑II scanner to identify the fault area.
- Loose or faulty gas cap
- Faulty oxygen (O2) sensor
- Mass airflow (MAF) or MAP sensor problems
- Ignition system faults (spark plugs, ignition coils)
- Vacuum leaks
- Exhaust or catalytic converter issues
- Fuel system problems (injectors, fuel pressure)
- Engine misfire or severe fuel trimming issues
Most codes point to a fault that should be diagnosed and repaired. If the light is blinking, stop driving safely and seek immediate assistance; a blinking CEL typically signals a severe issue that can damage the catalytic converter or others if ignored.
Blinking vs. steady CEL
A blinking CEL indicates a misfire or other condition that can cause catalytic converter damage; treat it as urgent. A steady CEL usually means a fault that should be addressed soon, but driving to a repair shop is often acceptable, depending on symptoms and codes.
What the Maintenance Required Light Means
The maintenance required light is not a diagnostic warning. It signals that the vehicle’s scheduled service interval has been reached or is approaching, based on mileage or time, and may be reset after service. Exact tasks vary by make and model, but the goal is to keep the car running reliably and within maintenance guidelines.
Common maintenance tasks prompted by the MR light include the following:
- Oil and oil filter change (at the manufacturer’s interval)
- Brake system inspection
- Fluid checks and top-ups (coolant, transmission, brake, power steering)
- Air filter replacement
- Tire rotation and alignment check
- Cabin air filter replacement
- Model-specific items (spark plugs, timing belt/chain if applicable, coolant flush)
After the scheduled maintenance is performed, the MR light is typically reset or will auto-clear after the next programmed interval. Consult your owner’s manual for exact reset steps and maintenance schedules tailored to your vehicle.
Summary
In short, the check engine light warns of a diagnosable engine or emissions fault that requires inspection and possible repair, while the maintenance required light is a proactive reminder to perform routine service on schedule. Treat a blinking CEL as urgent and MR as a planning cue to maintain reliability, performance, and emissions compliance. Keeping up with both types of alerts helps protect the engine and extend the vehicle’s life.
What is the most common check engine light on a Jeep Wrangler?
Common check engine light codes on a 2025 Jeep Wrangler include P0300 (random/multiple misfire), P0420 (catalyst system efficiency), P0171/P0174 (system too lean), and P0442/P0455 (evaporative emission control leak).
Is engine maintenance required the same as check engine?
The check engine light is sometimes confused with the maintenance required light, but the two are unrelated. The maintenance required light goes on when your car is due for routine service like an oil change. The check engine light is an indication that something unexpected has occurred.
Does Valvoline check engine codes?
This means you can visit most Valvoline shops and have a technician use a diagnostic scanner to retrieve the error codes from your vehicle's onboard computer at no cost.
Can I drive $1000 miles with the check engine light on?
The most common question we get is how long can you drive with check engine light on? The answer is it is safe to drive from 50-100 miles. To maintain your car's health, it is always better to get it checked immediately when you see the check engine light.