Powertrain, generic (extended)

P21A0 Cylinder 5 Air-Fuel Ratio Imbalance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

Likely causes

Cylinder 5 injector out of tolerance
Ignition or compression weakness at cylinder 5 affecting the roughness test
Software setting corrected by an update (e.g. Audi 3.0 TFSI)

Symptoms

  • Check engine light on
  • Possible P0305 or slight vibration at idle

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–1,500
Time0.5–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel injector

Related codes

P219AP219FP21A1P0305

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.