P21A0Cylinder 5 Air-Fuel Ratio Imbalance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P21A0 can only occur on engines with at least five cylinders. VW's 2014 specification books for the Golf, Jetta, Passat and Beetle with the 2.5 litre inline five list P219C to P21A0, one per cylinder, all judged the same way: the ECM briefly leans one cylinder, measures how much rougher the engine runs and derives an individual fuel correction; a result below 0.19 or above 1.50 is a fault. On a five-cylinder with a single front sensor, the bank code P219A belongs to the same engine. Six-cylinder users include Toyota's 2015 Tacoma 1GR-FE, Audi's 3.0 TFSI (software) and Kia's 2022 Carnival 3.5 GDI (injectors). Because the method uses roughness, a weak ignition coil or a compression problem in cylinder 5 can also influence the result.
- What you may notice
- Check engine light on
- Possible P0305 or slight vibration at idle
- Likely causes
- LikelyCylinder 5 injector out of tolerance
- PossibleIgnition or compression weakness at cylinder 5 affecting the roughness test
- RareSoftware setting corrected by an update (e.g. Audi 3.0 TFSI)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €0 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.