P2189: System Too Lean at Idle (Bank 2)

Severity: medium System: Fuel & Air System Can drive: caution

Quick answer: P2189 means the engine is running lean on Bank 2 at idle — the Bank 2 counterpart of P2187. As an idle-lean code, the classic cause is a vacuum/intake leak letting in unmetered air, with a dirty MAF or weak fuel delivery also possible. It only appears on engines with two banks and often pairs with P2187/P0174.

TL;DR

P2189 = system too lean at idle (Bank 2). Severity: medium. Drivable but may idle rough/stall. Top causes: vacuum/intake leak (50%), dirty MAF (25%), fuel delivery (15%), PCV (10%). A smoke test finds the leak fast.

Can I keep driving with P2189?

Yes, with caution.

IF it idles acceptably → drive short-term while diagnosing. IF it idles very rough, stalls or knocks → minimize driving; a sustained lean condition runs hot and stalling is a safety concern.

Symptoms

Check engine light on
Rough or unstable idle
Stalling at idle/stops
Hesitation off idle
Often a companion P2187/P0174 code

Top causes (ranked by probability)

Likely cause	Probability	Notes
Vacuum / intake leak (unmetered air)	50%	Worst at idle — smoke-test it
Dirty MAF sensor	25%	Affects both banks if dirty
Weak fuel delivery (pressure/injectors)	15%
Stuck-open PCV valve	10%

What does P2189 mean?

Technical explanation

P2189 mirrors P2187 for Bank 2: fuel trims show a lean condition at idle on the bank without cylinder 1. Unmetered air has the greatest effect at idle, so vacuum/intake leaks dominate, followed by a contaminated MAF, stuck-open PCV, or low fuel pressure. P2189 with P2187 (both banks) points to a shared cause.

In simple terms

P2189 means Bank 2 of your engine is running lean at idle — the same idle air-leak problem as P2187, just on the other side. A cracked vacuum hose or intake leak is the usual culprit; a smoke test finds it quickly.

How to diagnose P2189 (step by step)

Check whether P2187 is also present. Both banks lean at idle → shared cause (MAF/fuel/central leak); Bank 2 only → localized leak.
Read Bank 2 idle fuel trims. Confirm lean trims worst at idle.
Smoke-test the intake. Focus on Bank 2 runners, hoses and gaskets.
Clean/test the MAF. Especially if both banks are lean.
Check the PCV and fuel pressure. Rule out a stuck PCV or low fuel pressure.

Repair options & cost

Repair Bank 2 vacuum/intake leaks
Replace the PCV valve
Clean or replace the MAF sensor
Restore fuel pressure

DIY cost	$0–$250
Workshop cost	$100–$500
Repair time	20 min (hose/PCV) to 1.5 hours (fuel)

Costs are local ballpark ranges and vary by region and vehicle.

Tools you’ll need

OBD-II scanner (BlueDriver / ANCEL)
Smoke machine
MAF cleaner

Scan your car: recommended OBD-II scanners →

Vehicle-specific notes

Only engines with two banks have a Bank 2.
Diagnose with P2187/P0174 — they share causes.
Common on aging European V-engines with brittle plastic intake/PCV parts.

Common mistakes to avoid

Replacing the O2 sensor first
Skipping the smoke test
Ignoring the PCV system
Working on the wrong bank

Frequently asked questions

What is the difference between P2187 and P2189?

Both are idle-lean codes on different banks: P2187 is Bank 1 and P2189 is Bank 2. Seen together they usually share one cause.

Why is P2189 only at idle?

Unmetered air from a vacuum leak has the biggest effect at idle, where airflow is low, so the lean condition shows up mainly there.

Is P2189 serious?

Medium severity. The car runs but may idle rough or stall; address a sustained lean condition promptly.

P2189 summary

Meaning	System too lean at idle (Bank 2)
Severity	Medium
Safe to drive?	Yes, short-term (watch for stalling)
Top cause	Vacuum/intake leak (50%)
DIY cost	$0–$250
Shop cost	$100–$500