Dtc P0171: Fuel System Too Lean; Dtc P0172: Fuel System Too Rich - Honda S2000 Service Manual

DTC P0171: Fuel System Too Lean
DTC P0172: Fuel System Too Rich
NOTE: lf some of the DTCS listed below are stored at
the same time as DTCP0171 and/or P0'172,
troubleshoot those DTCS first, then recheck for P0171
andlot P0172.
P0107, P0108. P1128,P1129t Manifold Absolure
Pressure (MAP) Sensor
P0135: Primary Heated Oxygen Sensor (primary H02S)
( S e n s o r 1 ) H e a t e r
P0137, P0138: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S (Sensor 2) Heater
P1259: VTEC System
1. Check the fuel pressure (see page 11-'105).
ls luel pressure OK?
YES Go to step 2.
NO Check these items:
. l f t h e p r e s s u r e i s t o o h i g h . C h e c k t h e f u e l
pressure regulator, and the fuel return pipe.l
. l f t h e p r e s s u r e i s t o o l o w . C h e c k t h e f u e l p u m p ,
the fuel feed pipe, the fuel filter, and the fuel
pressure regulator.l
2. Start the engine. Hold the engine at 3,000 rpm with
no load (in neutral) until the radiator fan comes on,
3 . C h e c k t h e p r i m a r y H O 2 S ( S e n s o r 1 ) o u t p u t w i t h t h e
scan tool.
Does it stay less than 0.3 V or more than 0.6 V ?
YES Replace the primary HO2S (Sensor 1), I
NO Go to step 4.
4. Turn the ignition switch OFF.
5. With a vacuum pump, apply vacuum to the EVAP
canister purge valve from the intake manifold side.
Does it hold vacuum?
YES Check the valve clearances and adjust if
necessary. lf the valve clearances are OK, replace
the fuel injectors.l
NO Replace the EVAP canister purge valve. t
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