System too lean at idle (Bank 1)
What P2187 means
Your car's computer set P2187: System too lean at idle (Bank 1). It belongs to the fuel and air metering group of codes. It is a generic code, so it means the same thing on every make. The check engine light usually comes on once the fault has been seen on two drives in a row. Until then it shows up as a pending code.
Can I keep driving? Usually safe to drive for now, but get it checked soon. Left alone it can lower fuel economy, fail an emissions test or lead to a bigger repair.
Common causes
- Vacuum leak (cracked hose, PCV, intake gasket)
- Dirty or failing MAF sensor
- Weak fuel pump or clogged fuel filter
- Exhaust leak before the upstream O2 sensor
Fix the cheapest, most likely cause first. Clearing the code without a repair only turns the light off until the fault comes back.
Check it yourself
Watch long-term fuel trim. Above about +10% means the computer is adding a lot of fuel. If trim drops at higher RPM, a vacuum leak is likely.
Torque Deck reads P2187 with a cheap Bluetooth OBD2 adapter. It also shows the freeze frame (engine conditions at the moment the code set) and the live data you need to narrow it down.
Related codes
This page explains what the code usually means. It is not a diagnosis of your car. When in doubt, ask a mechanic.