P219B: Bank 2 Air-Fuel Ratio Imbalance
What to do
Ask whether the same fault is stored for the other bank. If both banks are affected, the cause is something shared — fuel pressure, fuel quality, or an airflow sensor — not a set of bad injectors, and that is a completely different repair.
Ask for the bank to be confirmed against the manufacturer's diagram before any part is replaced. Bank 2 is not always the side you would expect.
Ask about an intake leak as well as the injectors. A leaking gasket at a single intake runner leans one cylinder, which is exactly what this detects, and it is a much cheaper repair.
Mention any rough idle, however slight, since idle is where an imbalance shows first.
What this code means
The cylinders on bank 2 are not receiving the same air-fuel ratio as each other.
The mechanism is bank 1's — the module resolves individual cylinder signatures in the wideband oxygen sensor signal and finds them unequal. What a bank 2 code adds is the comparison, and on a V engine that comparison is genuinely decisive.
- One bank imbalanced, the other even — the cause is local to this bank. Its injectors, its intake runners, its own fuel supply if the banks are fed separately.
- Both banks imbalanced — look for something shared. A failing airflow sensor, fuel pressure, or fuel quality affect every cylinder, and the module reports it as imbalance on both sides.
That second case is worth stating plainly because it changes the repair completely. Both banks imbalanced is not eight bad injectors — it is one thing upstream of all of them.
Bank identification is the usual trap. Bank 1 is the bank containing cylinder 1, which is not always the side nearest the front and differs between manufacturers. Confirm against the manufacturer's diagram before working on anything.
An intake leak deserves specific mention on a V engine. The two banks share a plenum on most designs, but each runner is its own path — so a leaking gasket at one runner leans that cylinder alone, which is exactly what this code detects and what no fuel trim would reveal.
Likely causes
Start here
- Vacuum leak in intake manifold or hoses · moderate
- Worn or leaking fuel injectors · specialist
- Leaking intake manifold gasket · moderate
Less common
- Blocked or restricted injector nozzle · specialist
- Faulty mass air flow sensor · easy
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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