P2187 code meaning
System Too Lean at Idle (Bank 1)
Powertrain system Generic code P21xx codes Check engine light
What P2187 means
P2187 means the long-term fuel trim of bank 1 has to add more fuel than allowed in the idle and low-load range. Many systems, especially Bosch ones, split mixture adaptation into an additive part, which dominates at low airflow, and a multiplicative part for load. An air leak adds a fixed amount of unmeasured air, which matters most at idle, so it shows up in the additive part. GM's 3.6 V6 engines set the code above 7 % (2005) or 6.1 % (2008 LLT, at 520 to 1120 rpm, 1.7 to 7.8 g/s and coolant above 60 °C), and GM's 2024 tables above about 5.5 %, over two trips. On the Opel/GM 2.0 turbo in the Saab 9-5 (2010) the weighted long-term trim must exceed its limit for 4 s continuously or 50 s in total (Type B). Audi traced P2187 with P2279 on 2.0 TFSI engines to a crankcase ventilation valve that let boost into the crankcase; Mazda found A/F sensor wiring on the CX-7 2.3 turbo shorted after brake fluid was spilled on it.
P2187 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2187
- Malfunction indicator lamp on
- Rough or hunting idle, hissing from the engine bay
Common causes of P2187
- Most likelyAir leak after the air mass sensor, often at the crankcase ventilation
- Less likelyDamaged front oxygen or A/F sensor wiring
- Less likelyFuel pressure too low
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Intake manifoldPcv valveVacuum hoseMass air flow sensorOxygen sensor upstream
What each part of P2187 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 1 | Area: fuel and air metering. |
| 87 | The exact fault in that area. |
What to do next
- Note P2187 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2187
What does P2187 mean?
P2187 means "System Too Lean at Idle (Bank 1)". P2187 means the long-term fuel trim of bank 1 has to add more fuel than allowed in the idle and low-load range. It is a generic code, so it means the same on every make.
Is it safe to drive with P2187?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2187 fail an emissions test?
Yes, it can. P2187 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2187 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2187 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.