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.
Open the bonnetthe in-depth explanation
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 its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
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 an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P2183 The engine 2 coolant temperature sensor gives readings outside the normal range
- P2184 The engine 2 coolant temperature sensor gives a lower signal than normal
- P2185 The engine 2 coolant temperature sensor gives a higher signal than normal
- P2186 The engine 2 coolant temperature sensor fails now and then
- P2188 Mixture too rich at idle (bank 1)
- P2189 Mixture too lean at idle (bank 2)
- P218A The throttle actuator B control system idle position needs its learning
- P218C Throttle or fuel inhibit circuit B operates out of range or performs incorrectly
- 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
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 and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
