A lit Check Engine Light on your Audi’s dashboard may have you wondering:
Read on as we answer these questions and explore more about the Audi Check Engine Light.
This Article Contains:
- 7 Common Causes Behind an Audi Check Engine Light
- What to Do if the Audi Check Engine Light Turns On?
- How to Reset the Check Engine Light on an Audi?
- How Much Does it Cost to Diagnose an Audi Check Engine Light?
7 Common Causes Behind an Audi Check Engine Light
The Check Engine light (CEL) or Engine Management Light appears when your Audi’s Powertrain Control Module (PCM) detects an engine or emission control system issue. There can be different reasons that bring on the Audi Check Engine light, such as worn spark plugs or faulty sensors, as covered below:
1. Loose Gas Cap
The Evaporative Emissions Control (EVAP) system has a leak detection pump that pressurizes the system to check for fuel vapor leaks. A loose gas cap results in a significant pressure loss, which the EVAP system detects and relays to the PCM, triggering the Check Engine dashboard light.
Moreover, if the gas cap remains loose for long periods, contaminants can enter the fuel system, eventually damaging the fuel injectors.
Note: Your Audi may also have a dedicated gas cap warning light that comes on in the case of a loose gas cap.
2. Spark Plug Issues
A spark plug covered with engine oil, fuel, or carbon deposits or blistered due to heat won’t provide the required spark for igniting fuel in the engine. This can lead to an engine misfire and activate the Check Engine Light. On older vehicles, damaged spark plug wires can also bring on the Audi Check Engine Light.
3. Defective Ignition Coil
A bad ignition coil won’t deliver the high-voltage current needed by the spark plug for ignition, resulting in a misfire and an illuminated Check Engine Light. A faulty coil is more likely to affect older models, wherein a single ignition coil is responsible for firing all the spark plugs.
4. Faulty Oxygen Sensor (O2 Sensor)
There are two oxygen sensors in your Audi’s exhaust system — one before the catalytic converter and the other after it. You can get the Check Engine dashboard light if the reading from an oxygen sensor is outside the normal range or if there’s slow or no response. This can happen if an oxygen sensor malfunctions due to damaged wiring, water exposure, reference electrode contamination, thermal shock, or a broken sensing element.
5. Bad Mass Airflow Sensor (MAF Sensor)
The output from a defective Mass Airflow sensor (MAF sensor) can be inconsistent or outside the desired range. This causes the PCM to turn on the Audi’s Check Engine Light and store a related trouble code.
An MAF sensor can go bad due to contamination of its sensing elements, damaged circuit wiring or connector, and physical damage from excessive vibrations. You may experience symptoms like reduced engine performance and fuel economy due to an MAF sensor issue.
6. Damaged Catalytic Converter
The catalytic converter in the exhaust system turns harmful gases, like carbon monoxide and nitrogen oxides, into relatively safer gases, such as carbon dioxide and nitrogen. The O2 sensor downstream of the converter monitors if it’s working fine.
A clogged catalytic converter can cause a buildup of exhaust gas in the engine, impacting combustion and prompting the PCM to activate the Check Engine Light. Your Audi’s gas mileage may also suffer.
7. Turbocharger Problems
An insufficient turbocharger boost due to a vacuum leak or faulty boost control solenoid valve can register a fault code and trigger the Audi Check Engine Light.
Next, we’ll see how to deal with an illuminated Audi Check Engine Light.
What to Do if the Audi Check Engine Light Turns On?
The Check Engine Light can appear in different forms. Here are three common cases of an active Audi Check Engine Light:
A. Steady Check Engine Light
You can still drive with a steady Check Engine Light, but it’d be best to have your Audi vehicle inspected by a mechanic soon to prevent the existing emission or engine problems from worsening.
B. Check Engine Light with Performance Issues or EPC Light
If you notice reduced performance along with an illuminated Engine Management Light or CEL, your Audi may have entered “limp mode.” The Audi EPC (Electronic Power Control) system activates this mode to avoid engine damage, and an EPC light also appears on the dashboard.
As driving with active limp mode can be difficult, have a mobile mechanic come to you to inspect your vehicle for engine or transmission issues.
C. Flashing Check Engine Light
You shouldn’t drive your vehicle with a blinking Check Engine Light as it indicates serious trouble requiring immediate attention. A flashing Check Engine Light generally results from frequent engine misfires, which can harm the catalytic converter if left unchecked.
Get your vehicle towed to a workshop if a flashing Check Engine Light comes on.
After fixing the malfunctioning parts on your Audi vehicle, the mechanic will reset the Check Engine Light.
Keep reading to find out how.
How to Reset the Check Engine Light on an Audi?
The Audi Check Engine Light automatically goes off after a certain number of driving cycles if you’ve addressed its underlying issue. However, it’d be better to reset it immediately after the mechanic performs the repair work. This will help ensure the CEL doesn’t reactivate due to an overlooked problem.
Here are the two ways a mechanic would reset the Audi Check Engine Light:
A. Using an OBD II scanner
- Locate the OBD II port.
- Turn off the engine and connect the OBD II scanner to the port.
- Turn the ignition key to the “on” position.
- Press the “erase” or “clear” button on the scanner to reset the OBD system.
- Turn the ignition key to the “off” position.
- Disconnect the scanner.
- Start the engine to see if the CEL has disappeared.
B. Disconnecting the battery
- Open the hood.
- Locate the battery’s negative terminal and disconnect the cable at it.
- Reconnect the cable after about 15 minutes.
- Start the engine to ensure the Check Engine Light doesn’t come on again.
Before the technician repairs your Audi, they’ll run a diagnostic test to detect the fault leading to an active CEL. Let’s see how much you’ll have to spend on this.
How Much Does it Cost to Diagnose an Audi Check Engine Light?
An Audi Check Engine Light diagnosis can cost you between $88-$209, depending on your vehicle’s model and year and the inspection fees. You may also have to bear additional repair charges if the mechanic replaces a part (like a faulty sensor) or performs an oil change service:
- Spark plugs: $35-$100 per spark plug
- Spark plug wires: $10-$125
- Oxygen sensor: $125-$390
- Oil change: $70-$95
Note: These estimates exclude labor charges.
The Check Engine Light on your Audi illuminates when its onboard computer detects emission control or engine problems. Addressing this warning light soon can help prevent engine performance and gas mileage issues.
If you’re looking for a reliable and convenient fix, your best bet is AutoNation Mobile Service.
We’re a mobile auto repair service that can cater to your Audi’s Check Engine Light and other services like an oil change right in your driveway.
Contact us, and our experienced technicians will get your Audi up and running in no time.