P1128moderate severityPowertrain
Long Term Fuel Trim System Too Lean
on 2012 Kia Forte 2.4L I4 · FWD
What this code means
The PCM has detected that the long-term fuel trim system correction has exceeded the lean limit. The entire fuel system is consistently lean beyond the PCM correction capability.
Symptoms
- Check Engine Light
- Rough idle
- Hesitation
- Poor acceleration
- Possible misfires at idle
Common causes
- Large vacuum leak
- Failing fuel pump with low pressure
- Clogged fuel filter
- MAF sensor contamination under-reporting airflow
- Intake gasket leak
Diagnostic steps
- Check system fuel trim values on scan tool
- Perform comprehensive vacuum leak test
- Test fuel pressure at idle and under load
- Clean or replace MAF sensor
- Inspect intake manifold gaskets
Repair notes
Find and repair the vacuum leak or fuel delivery issue causing the lean system fuel trim.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1