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EPC and Check Engine Light on my 2017 S5 Cabriolet, reduced power

0

Mike T. · rep 0 · May 26, 3:48 AM · 1 replies · solved · Question

Vehicle: 2017 Audi S5 Cabriolet

Hi all,

I'm a bit worried about my 2017 Audi S5 Cabriolet. Yesterday, while driving, both the EPC (Electronic Power Control) light and the Check Engine Light (CEL) came on simultaneously. Immediately after, I noticed a significant reduction in power. The car felt sluggish and didn't want to accelerate properly.

I pulled over, turned the car off and on, and the lights were still there, and the power reduction remained. I'm afraid to drive it much like this. I haven't noticed any strange noises or smoke, just the lights and the lack of power.

Has anyone experienced this specific combination on their B9 S5? What could be the potential causes? I'm hoping it's not something major.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 26, 3:48 AM

0

ClearTheCode admin answer:

The simultaneous illumination of the EPC and Check Engine Light, coupled with reduced power (often referred to as 'limp mode'), is a critical warning in your 2017 Audi S5 Cabriolet. This typically indicates a serious engine or powertrain management issue. Here are the most common causes:

  1. Ignition System Failure: Faulty spark plugs or ignition coils are very common culprits. If one or more cylinders are misfiring, the engine control unit (ECU) will detect this and trigger both lights. Common OBD-II codes would be P0301-P0306 (Cylinder Misfire Detected, with the last digit indicating the cylinder number).
  2. Fuel System Issues: Problems with fuel injectors, a clogged fuel filter, or a failing fuel pump can lead to insufficient fuel delivery, causing misfires and reduced power. You might see codes related to fuel trim or misfires.
  3. Throttle Body Malfunction: The EPC light specifically relates to the electronic throttle body. If the throttle body is dirty, failing, or has a wiring issue, it can prevent proper air intake and cause limp mode. Codes like P2101 (Throttle Actuator Control Motor Circuit Range/Performance) are possible.
  4. Boost Leak/Turbocharger Issue: Given it's an S5, a significant boost leak (e.g., a cracked charge pipe) or an issue with the turbocharger itself (e.g., wastegate malfunction) can cause severe power loss and trigger these lights. Codes like P2279 (Intake Air System Leak) or P0299 (Turbo/Super Charger Underboost) could appear.
  5. Carbon Buildup: Direct injection engines like Audi's 3.0T V6 are prone to carbon buildup on the intake valves, which can restrict airflow and cause misfires, especially as the car ages. This is a longer-term issue but can manifest suddenly.

When to see a shop:

  • Immediately: Do not continue to drive the vehicle with both the EPC and Check Engine light on and reduced power. Driving in limp mode for extended periods can potentially cause further damage to the engine or catalytic converter.
  • Tow it: Have your S5 towed to an Audi specialist or dealership. They will need to perform a comprehensive diagnostic scan to read the specific fault codes stored in the ECU. These codes are crucial for accurately diagnosing the problem and will guide the technician to the exact component that needs attention. Attempting to clear the codes without fixing the underlying issue is not recommended, as the problem will likely return and potentially worsen.
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