Honda Accord 2008 Manual page 430

07/11/02 09:04:06 61TA0000_110_0111
DTC P0171: Fuel System Too Lean
DTC P0172: Fuel System Too Rich
NOTE:
• Before you troubleshoot, record all freeze data and
any on-board snapshot, and review the general
troubleshooting information (see page 11-3).
• If any of the DTCs listed below are indicated at the
same time as DTC P0171 and/or P0172, troubleshoot
those DTCs first, then recheck for P0171 and/or P0172.
P0101, P0102, P0103: Mass air flow (MAF) sensor
P0107, P0108, P1128, P1129: Manifold absolute
pressure (MAP) sensor
P0133, P1172, P1157, P2195, P2238, P2252, P2A00: Air
fuel ratio (A/F) sensor (Sensor 1)
P0134, P0135: Air fuel ratio (A/F) sensor (Sensor 1)
heater
P0137, P0138, P0139: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S (Sensor 2) heater
P2646, P2647, P2648, P2649: VTEC system
P0443, P0496: EVAP canister purge valve
1. Check the fuel pressure (see page 11-361).
Is the f uel pressure OK ?
YES − Go to step 2.
NO −
• If the pressure is too high, replace the fuel
pressure regulator (see page 11-376), then go to
step 7.
• If the pressure is too low, check the fuel pump,
the fuel feed pipe and the fuel filter. If they are
OK, replace the fuel pressure regulator (see page
11-376), then go to step 7.
2. Check for vacuum leaks at these parts:
• PCV valve
• PCV hose
• EVAP canister purge valve
• Throttle body
• Intake manifold
• Brake booster
• Brake booster hose
• Intake air duct
Are the parts OK ?
YES − Go to step 3.
−
NO Repair or replace parts with leaks, then go to
step 7.
3. Start the engine. Hold the engine speed at
3,000 rpm without load (A/T in P or N, M/T in
neutral) until the radiator fan comes on, then let it
idle.
4. Check for these conditions:
• Engine coolant temperature (ECT SENSOR 1)
above 158 °F (70 °C)
• A/T in N, M/T in neutral
• All electrical loads off
5. Monitor the ENGINE SPEED in the DATA LIST with
the HDS, and hold the engine speed at 2,500 rpm.
Once the engine speed is met, hold the accelerator
pedal steady for more than 10 seconds.
Did the engine speed vary more than 100 rpm f rom
2,500 rpm?
−
YES Repeat step 5.
NO − Go to step 6.
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(cont'd)
11-111