Please note: If the red engine management light stays on when you turn on the ignition or comes on while you’re driving, it means your engine has a serious fault and you should pull over and seek roadside assistance.
If your dashboard is displaying the amber engine management light symbol, your powertrain may have a problem. This error may be caused by something simple, or it could be a more serious issue. It's important to find out what the problem is and fix it.
Once you have solved the issue, you may find that the amber engine management light remains on due to a glitch. In this case, there are a few easy ways to make the light switch off. We’ll explain these below.
We’ll also show you how to determine the cause of any fault.
The easiest way to determine a fault causing the amber engine management light to come on is to use an OBD2 (on-board diagnostic) scanner. This device can be purchased online for around £20. Simply connect the OBD2 scanner to the connection port, which should be located under your dashboard on the passenger side. Almost all cars built after 2000 have this port.
After connecting the OBD2, turn off all connected gadgets then turn on your ignition. Press the "READ" button and any error codes will be displayed. Note down the codes then consult your car's handbook to find out what the fault is. If you don’t have your handbook, the manual that came with the scanner should tell you what the code(s) mean.
Next, press "ERASE" (or "CLEAR" on some scanners), which will clear all the error codes. If all the error codes are cleared, the amber engine management light will go off.
If you believe there are no issues with your engine, but the engine management light remains on, there are a number of ways to clear it.
Disconnect your car’s battery cables
One of the best known methods is to disconnect your car's battery cables. Use a wrench to remove positive and negative cables. Next, drain any residual current by holding down the horn for half a minute.
Wait around 15 minutes, then reconnect the battery cables. Check the error codes have been deleted and the engine management light has gone off. If the light returns, then you probably have an issue that requires the attention of a mechanic.
Turn the ignition on and off
An even simpler way to clear the engine management light is to turn the ignition on and off. This approach achieves the same outcome as the previous step, but without disconnecting the battery. Turn the ignition on and off three times, pausing a second between each cycle. The engine management light should go off. If it doesn’t, consult a mechanic.
Wait for the light to go off
If you notice the engine management light has come on, you could wait a few days to see if it goes off by itself. The light may come on due to some internal glitch. However, if the light remains on after this period, you should take steps to determine the problem.
You may also find that the light goes off for a period, then returns. Once again, this means you should take action to work out what the issue is. The easiest way is to take your car to a mechanic.
Unless it is due to a glitch, there are a number of possible reasons why your engine management light has come on.
The fuel cap is loose
A loose petrol cap is one of the most common causes for the engine management light to come on. Check the cap to see if it is damaged. If it is, replace the cap with a new one.
It’s the oxygen sensor
Your engine management light may come on if the oxygen sensor detects your car is running fuel which is too rich (less oxygen) or too lean (more oxygen). There may also be a fault with the sensor. This can be remedied by reprogramming/recalibrating the engine control unit (ECU). Your mechanic will be able to do this for you.
It’s the Diesel Particulate Filter (DPF)
Your engine management light may come on if there is a fault with your DPF - a filter that captures and stores exhaust soot and essentially helps make your diesel engine less polluting. A faulty differential pressure sensor may also mean the car's engine control unit doesn’t know the status of the DFP, which could cause the engine management light to come on.
The mass airflow sensor is damaged
Your car's mass airflow sensor helps your engine run efficiently. The engine control unit needs data from the mass airflow sensor to determine how much fuel to add to the combustion chambers so it matches the amount of air flowing into the engine. A missing, clogged or damaged air filter can itself damage the mass airflow sensor.
There’s an issue with the ignition system
In a petrol car, issues with your spark plugs or coils may cause the engine management light to come on.