P2187: your engine is running lean at idle
Running lean means the engine is getting more air, or less fuel, than the engine control unit is aiming for, and this code means bank 1 has been lean specifically while idling, for long enough, and by enough, that the computer's own correction has run out of room. Unlike the general lean code, this one is set only from what happens at idle, not from driving generally. It's a symptom the engine reports about itself, not a statement about which part is to blame.
You might notice
- The engine may idle roughly, hesitate, or feel like it's about to stall
- The engine warning light comes on
- lean
- — getting more air, or less fuel, than the computer is aiming for
- bank 1
- — the side of the engine that has cylinder number 1
What the code itself says
P2187 is a powertrain (engine, gearbox and drive system) code, and the 2 after the letter means it is a generic code with a standard meaning.
Grouped here as: Engine running, fuelling and misfires — Air metering, fuelling, ignition, misfire, idle, boost, knock, oxygen sensors and the catalyst, all working together in the running engine. That grouping is ours, to help explain the code. The code's official family is the letter at the start.
This page is generic. Your car isn't.
A code on its own only tells you what the sensor saw, not what's actually wrong — and that changes next to your other codes. Read this one together with the rest of your scan and we'll work out what's really going on.
Stop reading. Start diagnosing.
Two minutes, free, and it'll be about your car rather than every car.