P2187: Mixture too lean at idle (bank 1)
At idle, bank 1 has too much air or too little fuel. It is nearly always an air leak: a split vacuum hose, a gasket or the PCV valve.
| Code | P2187 |
|---|---|
| System | Engine and transmission |
| Group | P21xx, Throttle, injection and emissions |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P2187 means
At idle, the ECU has to add a lot of fuel on bank 1 and reaches its limit. Very little air goes in at idle, so even a small vacuum leak has a big effect on the mixture. That is why this code usually points to an air leak.
Most common causes
- Split, loose or chafed vacuum hose
- Broken or disconnected crankcase ventilation (PCV) valve or hose
- Leaking intake manifold or throttle body gasket
- Leaking brake servo hose
- Dirty or faulty mass air flow sensor
- Low fuel pressure or dirty injectors
Symptoms
- Engine warning light on
- Rough or hunting idle
- Hissing sound from the engine bay
- Engine tends to stall when stopping
Can you drive with P2187?
With care The car can be driven, but find the leak soon: a lean mixture makes the idle worse and can lead to misfires.
How to check it
Check live fuel trims at idle and then at 2,500 rpm: if they are high at idle and move towards zero as revs rise, it is almost certainly an air leak. Listen for a hiss with the engine running.
How to read and clear P2187 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P2187 with this same explanation and whether it’s confirmed, pending or permanent.
With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.
Similar codes
- P2146 Fuel injector group A supply voltage circuit or open
- P2177 System too lean off idle (bank 1)
- P2178 Mixture too rich away from idle (bank 1)
- P2179 Mixture too lean away from idle (bank 2)
- P2188 Mixture too rich at idle (bank 1)
- P2189 Mixture too lean at idle (bank 2)
- P2191 Mixture too lean at higher load (bank 1)
- P2195 Oxygen sensor signal biased or stuck lean (bank 1, sensor 1)
- P2100 Throttle actuator A control motor circuit open
- P2101 Throttle actuator A control motor circuit range or performance
- P2102 Throttle actuator A control motor circuit low
- P2104 Throttle control system: forced idle
P2187 is a generic code, so it means the same on any make, for example on Alfa Romeo, Dacia, Kia, Nissan, Opel / Vauxhall, Škoda. See what Final OBD does on your car in makes and models.
What does code P2187 mean?
At idle, the ECU has to add a lot of fuel on bank 1 and reaches its limit. Very little air goes in at idle, so even a small vacuum leak has a big effect on the mixture. That is why this code usually points to an air leak.
Can you drive with P2187?
The car can be driven, but find the leak soon: a lean mixture makes the idle worse and can lead to misfires.
How do you clear P2187?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P2187 comes back.
Read it on your car
Final OBD reads the faults of every control unit for free, including each make’s own codes, and with Pro explains each one in plain English. Free clears engine faults at no cost.
Coming soon
Mid to late October 2026
If you want to try it in your car before anyone else, send us your email and we will add you as a tester.
info@finalobd.com