What does code P2189 mean?

P2189 means idle-specific lean condition on bank 2. It’s moderately serious — you can usually keep driving gently, but diagnose it soon.

How is this different from P0171/P0172?

Scope: P0171-family means the correction maxed out overall; P2187-family means specifically at idle. The idle-only version usually has a smaller, more findable cause — treat it as a head start.

Why does my idle also surge with this code?

Same root: the computer chasing a mixture it can't balance at low airflow. Fix the lean/rich cause and the surge typically leaves with it.

P2189 — System Too Lean at Idle (Bank 2)

Moderate

Quick answer

P2189 means idle-specific lean condition on bank 2. First move: compare bank trims: both banks lean at idle = shared leak (intake, PCV); bank 2 only = that side's gasket or injectors.

What it means

P2189 reports that idle-specific lean condition on bank 2.

These codes are the fuel-trim verdicts scoped to idle only — and that scoping is the diagnostic gift. A mixture problem that exists only at idle is dominated by fixed-quantity causes: a vacuum leak (fixed extra air, huge at idle, diluted at speed) or a leaking injector/purge valve (fixed extra fuel, same math in reverse).

The steps below run cheapest-first — because in this family, the cheap causes really are the common ones.

P2189 symptoms: what you'll notice

Rough, uneven idle that smooths out as soon as you drive off.
Stumbling or stalling at stops, often worse with the AC running.
A hiss from the engine bay at idle if a vacuum leak is the cause.
Idle speed surging as the computer chases the mixture.

Common causes

Ordered from most to least likely.

1.

See the diagnosis steps

This family shares its suspect list; the steps walk it in cost order.
2.

Wiring or connector damage

The universal suspect for circuit-flavored codes.
3.

The component named by the code

Condemned by measurement, never by guess.

How to fix it: diagnosis, step by step

Cheapest and most likely checks first.

1 Confirm the idle-only pattern

Watch long-term fuel trim at idle versus at 2,500 RPM. Big correction at idle that fades with RPM is the fixed-quantity signature this family exists to report.
2 Lean codes: hunt the leak

Intake boot, vacuum hoses, PCV, intake gaskets, purge line — the full hunt is our vacuum leak guide, spray test and all.
3 Rich codes: find the fuel

Pinch the purge line at idle (trims snap back = purge valve), check fuel pressure, and consider a leaking injector — plug reading finds the wet cylinder.

Parts & tools you may need

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Related codes

Frequently asked questions

What does code P2189 mean?: P2189 means idle-specific lean condition on bank 2. It’s moderately serious — you can usually keep driving gently, but diagnose it soon.
What does P2189 mean in plain words?: Idle-specific lean condition on bank 2. Compare bank trims: both banks lean at idle = shared leak (intake, PCV); bank 2 only = that side's gasket or injectors.
How is this different from P0171/P0172?: Scope: P0171-family means the correction maxed out overall; P2187-family means specifically at idle. The idle-only version usually has a smaller, more findable cause — treat it as a head start.
Why does my idle also surge with this code?: Same root: the computer chasing a mixture it can't balance at low airflow. Fix the lean/rich cause and the surge typically leaves with it.