Honda 2004 Odyssey Service Manual page 441

PGM-FI System
DTC Troubleshooting (cont'd)
DTC P0171: Fuel System Too Lean
DTC P0172: Fuel System Too Rich
NOTE: If some of the DTCs listed below are stored at
the same time as DTC P0171 and/or P0172,
troubleshoot those DTCs first, then recheck for P0171
and/or P0172.
P0107, P0108, P1128, P1129: Manifold Absolute
Pressure (MAP) sensor
P0135: Primary Heated Oxygen Sensor (Primary HO2S)
(Sensor 1) heater
P0137, P0138: Secondary Heated Oxygen Sensor
(Secondary HO2S) (Sensor 2)
P0141: Secondary Heated Oxygen Sensor (Secondary
HO2S) (Sensor 2) heater
P0401, P1491, P1498: Exhaust Gas Recirculation (EGR)
system
P1259: VTEC System
1. Check the fuel pressure (see page 11-216).
Is f uel pressure OK ?
YES Go to step 2.
NO Check these items:
• If the pressure is too high, check the fuel
pressure regulator, and the fuel return line.
• If the pressure is too low, check the fuel pump,
the fuel line, the fuel filter, and the fuel pressure
regulator.
2. Start the engine. Hold the engine at 3,000 rpm with
no load (in Park or neutral) until the radiator fan
comes on.
3. Check the primary HO2S (Sensor 1) output with the
scan tool or the HDS.
Does it stay at less than 0.3 V or more than 0.6 V ?
YES Replace the primary HO2S (Sensor 1).
NO Go to step 4.
4. Turn the ignition switch OFF.
11-132
5. Connect a vacuum pump to the EVAP canister
purge valve on the EVAP canister side.
6. Disconnect the EVAP canister purge valve 2P
connector.
7. Start the engine.
Is there vacuum on the gauge?
YES Replace the EVAP canister purge valve.
Check the valve clearances, and adjust if
NO
necessary. If the valve clearances are OK, replace
the injectors.