P2187 on Audi
System Too Lean at Idle (Bank 1)
P2187 on Audi vehicles indicates system too lean at idle (bank 1). Au7o has documented this code across 1 Audi model — most commonly on S5. This code means the engine's computer has detected the air-fuel mixture on Bank 1 is too lean specifically at idle, while it stays acceptable at higher speeds. The computer monitors the oxygen sensors and has had to add significant fuel correction at idle to compensate. Because the fault appears mainly at idle, it usually points to a small vacuum or air leak that has a big effect when airflow is low. Symptoms often include rough or unstable idle, stalling, and hesitation when first taking off. Typical repair costs on Audi range from $600 to $1,200, depending on the specific model and root cause.
Common Causes of P2187
- •Small vacuum leak (hose, gasket, or fitting)
- •Intake manifold or throttle body gasket leak
- •Faulty or leaking PCV valve/hose
- •Dirty or failing mass airflow (MAF) sensor
- •Leaking or dirty fuel injectors
- •Faulty upstream oxygen sensor
- •Low fuel pressure at idle
- •Leaking brake booster or its vacuum hose
P2187 on Audi by Model
Audi S5(1 issue)
- PCV Valve (Crankcase Vent Valve) Failure (3.0T)2010-2017
The Audi S5 (2010-2017) with the 3.0T supercharged V6 has a chronic PCV valve (also called air-oil separator or crankcase vent valve) failure. The PCV valve diaphragm degrades over time, causing oil leaks, check engine lights, rough idle, and a loud squealing/whistling noise from the engine. The 3.0T PCV is located at the rear of the engine near the firewall, making it moderately difficult to access. Many B8/B8.5 S5 owners replace the PCV valve and water pump simultaneously to save on future labor costs, since both are common failure items. Audizine, ShopDAP, and Motor Werke report PCV failure as a near-certainty before 100,000 miles. The repair is moderate in cost but ignoring it leads to vacuum leaks and accelerated oil consumption.
Looking for P2187 on a different make?
View P2187 across all makes →Frequently Asked Questions
What does P2187 mean on Audi?▼
P2187 stands for "System Too Lean at Idle (Bank 1)." This code means the engine's computer has detected the air-fuel mixture on Bank 1 is too lean specifically at idle, while it stays acceptable at higher speeds. The computer monitors the oxygen sensors and has had to add significant fuel correction at idle to compensate. Because the fault appears mainly at idle, it usually points to a small vacuum or air leak that has a big effect when airflow is low. Symptoms often include rough or unstable idle, stalling, and hesitation when first taking off. On Audi specifically, this code is documented across 1 model.
What causes P2187 on Audi vehicles?▼
Common causes on Audi: Small vacuum leak (hose, gasket, or fitting), Intake manifold or throttle body gasket leak, Faulty or leaking PCV valve/hose, Dirty or failing mass airflow (MAF) sensor, Leaking or dirty fuel injectors. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P2187 on a Audi?▼
Repair costs on Audi range from $600 to $1,200, depending on the specific model and root cause.
Which Audi models have P2187 documented?▼
Au7o has documented P2187 on 1 Audi model: S5.