P2189: System Too Lean at Idle Bank 2
What to do
Expect a rough or uneven idle that clears once moving. Ask whether bank 1 shows the same code: if it does not, the leak is physically on this side of the engine and the search is much smaller than a general vacuum leak hunt.
What this code means
The lean-at-idle condition of P2187, on the second cylinder bank. The unmetered-air reasoning applies unchanged, and so does the one-bank-or-both narrowing set out at P2179.
What a single-bank lean-at-idle adds is a location. Intake manifold gaskets fail on one head at a time; so do injector seals; and the vacuum lines feeding one side of a V engine are physically separate from the other. So a lean condition confined to one bank at idle is not merely a leak — it is a leak on a known side of the engine, which is a genuinely narrowed search rather than a whole-intake inspection.
Likely causes
Start here
- Leaking intake manifold gasket · moderate
- Vacuum leak in intake manifold or hoses · moderate
- Disconnected or leaking vacuum hose · easy
Less common
- Exhaust leak before the sensor · moderate
- Faulty oxygen sensor · moderate
- Leaking injector seal · moderate
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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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
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