The P2187 code on your 2021 Cadillac XT5 indicates the fuel system is running too lean during idle and low-speed operation on bank 1. This code affects your XT5's 2.0L turbocharged or 3.6L V6 engine, signaling excessive lean conditions on the driver's side cylinder bank.
Understanding P2187 on Cadillac XT5
Code P2187 indicates lean conditions at idle and just off idle - the low-load operating range. The ECM has exhausted its positive fuel trim adjustment capability trying to compensate for excess air or insufficient fuel on bank 1 at these operating conditions.
Common Symptoms
- Check engine light on
- Rough idle
- Idle speed hunting or fluctuating
- Slight hesitation from stop
- May idle rough when cold
- Possible lean misfire at idle
- Improved operation at higher speeds
Primary Causes
- Vacuum leak on bank 1 intake
- Intake manifold gasket leak
- PCV system leak
- Brake booster vacuum leak
- Bank 1 injector O-ring air leak
- Faulty MAF sensor reading low
- Bank 1 O2 sensor reading falsely rich
Diagnostic Procedure for 2021 XT5
Monitor bank 1 fuel trims at idle - positive values above 20-25% confirm lean condition. Compare to bank 2 trims. Perform thorough smoke test on bank 1 intake runners, manifold gasket, and vacuum lines. Check PCV valve and hoses. Test brake booster for vacuum leaks. Check MAF sensor readings. Swap O2 sensors between banks if sensor fault is suspected.
Repair Solutions
Repair vacuum leaks found during smoke testing. Replace leaking intake manifold gaskets. Replace cracked or damaged vacuum hoses. Address PCV system leaks. Repair brake booster vacuum leaks. Replace faulty MAF or O2 sensors. After repairs, clear codes and verify fuel trims normalize at idle.