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High Oil Consumption & Rough Idle on 2016 A4 2.0T - PCV Valve?

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Mike T. · rep 0 · May 25, 3:15 AM · 1 replies · solved · Question

Vehicle: 2016 Audi A4 2.0T Premium Plus

Hello fellow Audi owners,

I'm experiencing some concerning issues with my 2016 Audi A4 2.0T Premium Plus (B9 chassis). Over the past few months, I've noticed a significant increase in oil consumption – I'm adding a quart every 1,500-2,000 miles, which seems excessive. Recently, the car has developed a rough idle, especially when cold, and the check engine light came on.

I scanned the car and pulled a P0171 code (System Too Lean Bank 1). From what I've read online, this, combined with high oil consumption, often points to a failing PCV (Positive Crankcase Ventilation) valve on these 2.0T engines. Has anyone else dealt with this specific combination of symptoms on their B9 A4?

Is replacing the PCV valve a straightforward DIY, or is it better left to a professional? Any insights or experiences would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:15 AM

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ClearTheCode admin answer:

  1. Likely Culprit: Based on your symptoms of high oil consumption, a rough idle, and the P0171 (System Too Lean Bank 1) diagnostic trouble code, a failing PCV (Positive Crankcase Ventilation) valve is indeed a very strong suspect for your 2016 Audi A4 2.0T (EA888 Gen 3) engine.

  2. How a Failing PCV Causes These Issues:

    • Oil Consumption: A failed PCV valve can allow excessive vacuum in the crankcase, pulling oil vapor into the intake manifold, where it's burned off, leading to increased oil consumption.
    • Rough Idle/Lean Condition: A common failure mode for these PCV valves is a torn diaphragm, creating a vacuum leak. This unmetered air entering the intake system causes the engine to run lean (P0171) and can result in a rough idle, especially at low RPMs.
    • Other Potential Codes: You might also see P0507 (Idle Air Control System RPM Higher Than Expected) or P0174 (System Too Lean Bank 2, if applicable) in some cases.

  3. DIY Feasibility: Replacing the PCV valve (often referred to as the oil separator) on the EA888 Gen 3 engine is a manageable DIY job for someone with moderate mechanical skills. It's located on top of the engine, under the engine cover. You'll need basic hand tools (sockets, Torx bits) and possibly a new gasket for the PCV unit.

  4. Steps to Consider:

    • Ensure the engine is cool before starting.
    • Remove the engine cover.
    • Disconnect electrical connectors and vacuum lines from the PCV unit.
    • Unbolt the PCV valve from the cylinder head.
    • Clean the mating surface thoroughly.
    • Install the new PCV valve with a new gasket, ensuring proper torque.
    • Clear the fault codes after replacement.

  5. When to See a Shop: If you're uncomfortable working around engine components, diagnosing vacuum leaks, or if the issue persists after replacing the PCV, it's best to consult a qualified Audi technician. A professional can perform a proper smoke test to confirm vacuum leaks and rule out other potential causes for the lean condition, such as a faulty MAF sensor or fuel delivery issues.

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