Audi A3: 1.4 TFSI CZEA ACT solenoid fault — cyl 2 misfire P0302

The 1.4 TFSI CZEA engine uses Audi Active Cylinder Technology (ACT) which deactivates cylinders 2 and 3 at light load to improve fuel economy. The oil-pressure solenoid valves controlling the deactivation mechanism can fail or become blocked by oil sludge, causing cylinder 2 to misfire when the system attempts deactivation. The engine management unit logs fault code P0302 (cylinder 2 misfire detected). At idle or light load the car shakes noticeably. In persistent cases the ACT system requires disabling via a software update to prevent recurring misfires and potential catalytic converter damage.

• Check engine light with fault code P0302 — cylinder 2 misfire detected
• Rough idle or noticeable engine shake at light throttle loads
• Hesitation or stumble in the 1,500 to 2,500 RPM range
• Intermittent misfire that resolves at higher engine load when all four cylinders are active
• Fuel economy worse than rated if ACT is permanently locked out by the ECU

1. 1

   Test drive at steady very light throttle between 1,500 and 2,200 RPM and feel for engine roughness indicating a misfire.

2. 2

   Ask whether a software update has been applied by an Audi dealer to address the ACT solenoid fault.

3. 3

   Confirm regular oil changes have been performed — sludge is a primary cause of solenoid blockage.

4. 4

   If a workshop inspection is possible: Connect an OBD-II scanner and specifically check for P0302 or any ACT-related fault codes before the test drive.

Parts involved: Catalytic converter.

$600 to $2,200 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.

• “Has the check engine light appeared with a misfire code, particularly P0302 for cylinder 2?”
• “Has the Active Cylinder Technology (ACT) system been addressed or disabled by a software update from an Audi dealer?”
• “Has the engine oil been changed on schedule using the correct specification to prevent sludge blocking the ACT solenoids?”

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.