P2189 on Buick
System Too Lean at Idle (Bank 2)
P2189 on Buick vehicles indicates system too lean at idle (bank 2). Au7o has documented this code across 1 Buick model — most commonly on Enclave. P2189 means the engine computer detected that the air-fuel mixture on bank 2 is running too lean (too much air relative to fuel) specifically at idle. The computer watches the oxygen sensors and has been adding extra fuel (high fuel trim) to compensate, but the correction has reached its limit, indicating an unmetered air leak or a fuel-delivery shortfall. A lean condition at idle commonly causes rough idle, stalling, hesitation, or a surging engine. The usual culprits are vacuum/intake leaks downstream of the airflow sensor or anything restricting fuel.
Common Causes of P2189
- •Vacuum or intake manifold air leak (gaskets, hoses, PCV)
- •Dirty or faulty mass airflow (MAF) sensor
- •Clogged or weak fuel injectors on bank 2
- •Low fuel pressure (failing pump, restricted filter, weak regulator)
- •Leaking intake gasket or cracked intake boot
- •Faulty or contaminated oxygen sensor giving false lean signal
- •Exhaust leak ahead of the upstream O2 sensor
P2189 on Buick by Model
Buick Enclave(1 issue)
- Cold-Weather PCV Deposits Can Cause Reduced Power (PI0746)2008-2011
GM PI0746 covers 2008-2011 Buick Enclave vehicles with the 3.6L LY7 or LLT engine. After a cold start or low-ambient-temperature driving, condensation can freeze at the throttle-body base while engine vapors, fuel dilution and oil mist collect in the air-inlet duct. The condition can illuminate the MIL and cause poor performance or reduced acceleration.
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View P2189 across all makes →Frequently Asked Questions
What does P2189 mean on Buick?▼
P2189 stands for "System Too Lean at Idle (Bank 2)." P2189 means the engine computer detected that the air-fuel mixture on bank 2 is running too lean (too much air relative to fuel) specifically at idle. The computer watches the oxygen sensors and has been adding extra fuel (high fuel trim) to compensate, but the correction has reached its limit, indicating an unmetered air leak or a fuel-delivery shortfall. A lean condition at idle commonly causes rough idle, stalling, hesitation, or a surging engine. The usual culprits are vacuum/intake leaks downstream of the airflow sensor or anything restricting fuel. On Buick specifically, this code is documented across 1 model.
What causes P2189 on Buick vehicles?▼
Common causes on Buick: Vacuum or intake manifold air leak (gaskets, hoses, PCV), Dirty or faulty mass airflow (MAF) sensor, Clogged or weak fuel injectors on bank 2, Low fuel pressure (failing pump, restricted filter, weak regulator), Leaking intake gasket or cracked intake boot. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P2189 on a Buick?▼
Repair costs vary widely depending on the root cause and specific Buick model.
Which Buick models have P2189 documented?▼
Au7o has documented P2189 on 1 Buick model: Enclave.