Audi A1: 1.0 TFSI three-cylinder rough idle, misfire and early coil failure

The three-cylinder 1.0 TFSI in this A1 develops an uneven idle with vibration and occasional misfiring, with first signs reported from as little as 25,000 to 40,000 km — early enough that a car with modest mileage can already be doing it. Ignition coils on this engine commonly need replacing around 50,000 to 70,000 km, which is short by modern standards. A three-cylinder always idles with more character than a four, so the trap for a buyer is deciding what is normal: a slight thrum you can feel through the wheel at idle is the engine's nature, but a stumble, a shake that comes and goes, or a misfire you can feel through the car is a fault. Coils are cheap. Ignoring a persistent misfire is not, because unburnt fuel damages the catalytic converter.

• Uneven or lumpy idle, worst when the engine is cold
• Vibration through the steering wheel or seat at a standstill
• Occasional misfire — a stumble or hesitation as you accelerate
• Engine warning light, sometimes flashing
• Rough running that improves once the engine is fully warm

Be there for a cold start and pay attention to the first minute. Sit in the car as it idles from cold with everything switched off and feel the steering wheel and seat: a gentle even thrum is normal for a three-cylinder, but a shake that rises and falls, or a stumble where the engine nearly catches out, is not. Watch the tachometer for a needle that hunts rather than settling. Let it warm fully and check whether the idle smooths out, then check again with the air conditioning on, which loads the engine at idle and exposes a weak cylinder. On the drive, accelerate gently from low revs in a higher gear and feel for a hesitation or a jerk. Watch the dash throughout for an engine warning light, and treat a flashing one as a reason to stop. Ask when the spark plugs and ignition coils were last replaced and ask to see the invoice — on this engine that is a routine question, not an awkward one. If a workshop inspection is possible: ask for the stored misfire counters to be read, which name the cylinder even when the car is behaving.

Parts involved: Catalytic converter, Ignition coil.

$300 to $1,400 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “When were the ignition coils and spark plugs last replaced?”
• “Does it ever idle roughly or hesitate when you accelerate?”
• “Has the engine warning light ever come on?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.