The P1128 code in your 2022 Acura ILX indicates the fuel system is running too lean on bank 1. This Honda/Acura-specific code signals the ECU is adding maximum fuel but still can't achieve the correct air/fuel ratio.
Understanding Lean Conditions
A lean condition means there's too much air relative to fuel in the combustion mixture. The ECU can add fuel to compensate, but P1128 indicates it's reached its limit and the engine is still lean.
Common Causes of P1128
- Vacuum leaks (most common)
- Faulty MAF sensor
- Low fuel pressure
- Clogged fuel injectors
- Exhaust leak before O2 sensor
- PCV system issues
Symptoms of Lean Condition
- Check engine light on
- Rough idle
- Hesitation on acceleration
- Poor performance
- Possible engine knock
- Higher exhaust temperatures
ILX Engine Considerations
The ILX uses a naturally-aspirated engine that's sensitive to air/fuel ratios. Lean conditions affect both performance and can cause engine damage if severe.