Subaru 2009 IMPREZA Service Manual page 535

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed?
Check
EN(H4SO)(diag)-118
Yes No
Check the appro- Replace the mass
priate DTC using air flow and intake
the "List of Diag- air temperature
nostic Trouble sensor. <Ref. to
Code (DTC)". FU(H4SO)-34,
<Ref. to Mass Air Flow and
EN(H4SO)(diag)- Intake Air Temper-
86, List of Diagnos- ature Sensor.>
tic Trouble Code
(DTC).>