What is the reason for the engine fault light in Audi Q5?

[DeReese]

Audi Q5 generally has a self-inspection process for a few seconds after power-on, during which all indicator lights will illuminate. After the self-inspection is completed, under normal circumstances: 1. The lights will turn off: The airbag fault light will turn off. If the seat belt is fastened, the seat belt warning light will also turn off, and the remaining lights will stay on. 2. Normal: After the engine starts, normally only the water temperature light remains on, and all other lights will turn off. 3. Fault: If the engine light remains on after starting, it indicates an engine fault, and the information cannot be cleared. You need to go to a 4S store for inspection immediately. If you can confirm that the engine fault light is on, you can follow these steps: 1. Pull over and turn off the engine, wait for a few dozen seconds, and then restart to see if the engine fault light is still on. 2. If it is on, drive slowly to the 4S store for inspection and handling; if the engine fault light is off, avoid driving with high throttle or speed. 3. Even if the engine fault light is on, you may not feel any issues with the car (subjectively), but the car’s emission system definitely has a fault. Fuel efficiency will significantly decrease, and exhaust emissions will exceed standards, so you must go to a 4S store for inspection and repair.

[StBenjamin]

Last year when I was driving my Audi Q5, I encountered the issue of the engine malfunction indicator light coming on. It turned out to be due to a faulty oxygen sensor. My friend said this is quite common because the sensor monitors exhaust emissions and can trigger false alarms when dirty or damaged. Don’t panic if the light comes on—first, check if it’s a fuel quality issue. Using low-grade gasoline can clog the fuel system or cause excessive emissions. Worn spark plugs or severe carbon buildup can also trigger the light, so it’s recommended to replace spark plugs regularly. For turbocharged models, oil leaks or loose pipes are more serious and require immediate inspection. In my case, the dealership used an OBD scanner and found trouble code P0420—replacing the sensor fixed the issue. Never ignore it, as prolonged illumination could damage the catalytic converter, doubling the repair cost.

[StGavin]

When the engine warning light came on in my Audi Q5, I experienced it once and found out it was a fuel system issue. A friend who's a mechanic taught me step by step, saying it could be clogged fuel injectors or insufficient fuel pump pressure, causing an air-fuel mixture imbalance. In the electronic systems, failures like a faulty crankshaft position sensor are most common—it monitors engine speed and position, and if it fails, it triggers false alarms. A dirty throttle body or loose ignition coils can also easily trigger the light. DIY check suggestions: Connect an OBD scanner to read trouble codes—for example, P0171 indicates a lean mixture. Regular maintenance like using good engine oil and periodic carbon cleaning helps avoid breakdowns. In my case, cleaning the throttle body fixed it, costing just a few hundred bucks, saving a lot of hassle.

[LeSamuel]

I've been driving for decades. When the engine warning light comes on in an Audi Q5, it's mostly due to an emissions system malfunction. Common causes include aging oxygen sensors, which monitor exhaust quality and may falsely trigger the light due to carbon buildup; or a clogged catalytic converter, causing excessive backpressure that triggers the alarm. Minor issues like a loose fuel cap or a dirty air filter can also cause the light to come on. Don't delay if you notice it—stop immediately to check basic components to avoid damaging larger systems. Scanning for trouble codes promptly can quickly pinpoint the issue, such as P0300 indicating an ignition problem. Regular maintenance, like changing the air filter every six months, is crucial.