Fuel System Too Lean; Fuel System Too Rich - Honda Civic 2002-2003 Service Manual

PGM-FI System
DTe Troubleshooting (cont'd)
OTC P0171:
Fuel System
Too
Lean
OTC P0172:
Fuel System
Too
Rich
NOTE: If some of the DTCs listed below are stored at
the same time as DTC P0171 and/or POl72,
troubleshoot those DTCs first, then recheck for P0171
and/or POl72.
P0107, P0108, Pl128, Pl129: Manifold absolute
pressure (MAPI sensor
Pl162, Pl166, Pl167: A/F sensor (Sensor 11 heater
P0137, P0138: Secondary H02S (Sensor 21
P0141: Secondary H02S (Sensor 21 heater
P1259: VTEC system
1. Check the fuel pressure (see page 11-1451.
Is fuel pressure OK?
YES-Go to step 2.
NO-Check these items:
If the pressure is too high, replace the fuel
pressure regulator (see page 11-1521 .•
If the pressure is too low, check the fuel pump,
the fuel feed pipe, the fuel filter, and replace the
fuel pressure regulator (see page 11-1521 .•
2. Start the engine. Hold the engine at 3,000 rpm with
no load lin neutrall until the radiator fan comes on.
11-70
3. Turn the ignition switch OFF.
4. With a vacuum pump, apply vacuum to the
evaporative emission
(EVAP)
canister purge valve
(AI from the evaporative emission (EVAPI canister
side.
Does it hold vacuum?
YES-Check the engine valve clearances and adjust
if necessary. If the valve clearances are OK, replace
the injectors (see page 11-111)..
NO-Replace the EVAP canister purge valve .•
•
•