P0171
DTC P0171: Fuel System Too LeanSpecial Tools Required
Vacuum pump/gauge, 0 - 30 in.Hg A973X-041-XXXXX
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.
P0106, P0107, P0108, P1128, P1129: MAP Sensor
P1162, P1163, P1164, P1165: A/F Sensor (Sensor 1)*1
P1166, P1167, P1168, P1169: A/F Sensor (Sensor 1) Heater*1
P1149,P1157,P1158, P1159, P1162, P1163, P1164: A/F Sensor (Sensor 1)*2
P0134, P1166, P1167: A/F Sensor (Sensor 1) Heater*2
P0133, P1157, P2238, P2252, P2AOO: A/F Sensor (Sensor 1)*3
P0134, P0135: A/F Sensor (Sensor 1) Heater*3
P0137, P0138: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S (Sensor 2) Heater
P1259 (P2645)*3: VTEC System
*1: 2000-2001 M/T models
*2: 2002-2003 models
*3: 2004 model
1. Check the fuel pressure.
Is fuel 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 pipe.
- If the pressure is too low, check the fuel pump, the fuel feed pipe, 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 A/F sensor (Sensor 1) output with a scan tool or the HDS.
Does it stay at less than 0.3 V or more than 1.0 V?
YES - Replace the A/F sensor (Sensor 1).
NO - Go to step 4.
4. Turn the ignition switch OFF.
5. Disconnect the vacuum hose from the EVAP canister purge valve (A), and connect a vacuum pump to the hose.
Does it hold vacuum?
YES - Check the valve clearance and adjust if necessary. If the valve clearances are OK, replace the fuel injectors.
NO - Replace the EVAP purge valve.