Basic checks
Veepeak OBDCheck BLE
A Bluetooth LE adapter for reading standard engine codes and supported live data.
View on AmazonP2187
System Too Lean at Idle (Bank 1)
Moderate severity
This code means the engine's computer has detected that the air-fuel mixture is too lean (too much air, not enough fuel) specifically when the engine is idling on the first bank of cylinders. This indicates unmetered air entering the engine or insufficient fuel delivery.
System Too Lean at Idle (Bank 1)
Common causes
- high
Vacuum Leaks
Cracked or disconnected vacuum hoses, intake manifold gaskets, or PCV system components can allow unmetered air into the engine.
Typical part cost: $0-200 repair
- medium
Faulty PCV Valve/System
A stuck-open PCV valve or a leak in its hose can create a vacuum leak, especially at idle.
Typical part cost: $20-100 part
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First things to check
- 1Listen for vacuum leaks and visually inspect all vacuum hoses, intake manifold gaskets, and PCV system components.
- 2Perform a smoke test on the intake system to pinpoint vacuum leaks.
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Tools you may need
Already have a compatible scanner? Use it. If not, a Bluetooth OBD2 adapter can help you confirm engine codes and check supported live sensor data before replacing parts.
Regular diagnostics
vgate iCar Pro BLE 4.0
A Bluetooth LE adapter with an automatic sleep feature for routine code and sensor checks.
View on AmazonAnother option
OBDLink CX
A Bluetooth LE adapter to consider when comparing supported vehicles and diagnostic apps.
View on AmazonIllustrations shown, not product photos. Check vehicle, phone and app compatibility before buying. These adapters do not guarantee access to ABS, airbags or manufacturer-specific systems. Clearing a code does not repair the fault and can reset emissions readiness monitors.
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Related codes
See related trouble codes
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Frequently asked questions
What does 'lean' mean for an engine?
A 'lean' condition means there's too much air and not enough fuel in the air-fuel mixture. This can cause the engine to run hotter, lose power, and potentially damage components.
Why does P2187 only happen at idle?
Vacuum leaks have a greater impact at idle because engine vacuum is highest. At higher RPMs, the volume of air entering through the throttle body often overwhelms the effect of a small vacuum leak.
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