Amber — check soon
Check Engine
The engine control unit has found a fault and stored a code. This lamp has more than a hundred possible causes: from a loose fuel cap to misfires.
An amber lamp means you can drive on, but do not put it off. The car runs in a protective mode and usually drinks more.
What to do now
- Check that the fuel cap is tightened until it clicks — the most common and the cheapest cause.
- Listen to the engine: is it stumbling, has it lost power, is there smoke? If the lamp is BLINKING rather than steady, stop driving — that means misfires, and the catalytic converter is burning with them.
- Read the code with an adapter: without it every guess costs money.
Codes usually behind it
The lamp only says that something is wrong. The code says what exactly — read it with an adapter and look it up here.
P0171System too lean (bank 1) — air leak or not enough fuelP0300Random/multiple cylinder misfire detectedP0420Catalyst system efficiency below threshold (bank 1)P0455Evaporative emission system leak detected (gross leak)
What to read next
- The check light came on while driving
- Flashing rather than steady: the difference
- And if the lamp never comes on at all
A lamp is not a diagnosis. The same symbol lights up for a dozen different reasons, and only the code stored in the car tells them apart.
How it feels behind the wheel
The same fault shows itself in different ways. Each sign below says what to look at in the live data.
It stalls while drivingThe engine dies while the car is moving — at speed, in a corner or when lifting off. The steering and brakes go heavy at once.Hard to start when hotIt starts instantly from cold, but after a drive it cranks for a long time and catches reluctantly. Pressing the throttle sometimes helps.The temperature gauge is climbingThe needle goes above its usual place, there is a hot smell from under the bonnet, and the heater may blow cold on a hot engine.Knocking under loadUnder acceleration or on a hill the engine makes a metallic rattle, as if small change were being shaken. It goes away at steady throttle.The revs are capped and the car will not accelerateThe pedal is flat to the floor but the engine caps out around three thousand and goes no further. The car moves, but sluggishly, and overtaking is impossible. The check light is often on.The engine stumblesThe engine runs unevenly, the car shakes at idle, the exhaust note stutters. On the move the pull sags and consumption rises.Idle speed huntsThe tachometer needle wanders up and down with the car standing still: 1200, then 600. Sometimes the engine nearly stalls and picks up again.Fuel consumption has gone upYou refuel noticeably more often for the same driving. The lamp is usually off — the unit thinks it is coping.It jerks under accelerationAt steady throttle everything is fine, but under acceleration the car jerks or hesitates, as if the pedal was released for a moment.It cranks but will not startThe starter turns the engine over briskly, but it does not catch. Sometimes it catches and dies.The car has lost powerThe car moves, but sluggishly: flooring the throttle changes nothing, the revs climb reluctantly. Often the lamp is on as well.It stalls at idleAt the lights, or when you lift off, the engine dies. It usually restarts straight away.Slow to warm up, the heater blows coldThe temperature needle sits low for ages, the cabin stays cold, and on the motorway it gets worse. Consumption rises noticeably.It smells of petrolA fuel smell in the cabin or around the parked car. Sometimes with the Check Engine lamp on.Smoke from the exhaustVisible smoke from the tailpipe. The colour is the clue: white, blue and black mean entirely different things.Check engine came on after refuellingYou filled up, drove a few kilometres, and the light came on. The car drives exactly as before.The cooling fan runs all the timeThe fan roars right after starting and does not stop even on a cold engine or in frost.Cruise control stopped engagingThe button clicks but cruise never takes the speed — or it drops out after a few seconds.Check engine came on after a wash or heavy rainYou washed the car or drove through a downpour — and the light came on. It often clears itself in a day or two.
How the app helps
CarScan reads the codes behind the lamp through an OBD-II adapter, explains them in plain words and puts them into a report you can show to a mechanic.