P0172
DTC P0172: Fuel System Too RichNOTE: 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
P1162*5, P1166*3, P1167*6 (P0135)*4: A/F sensor (Sensor 1) heater*2
P0137, P0138: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S (Sensor 2) heater
P0401*3, P1491*3, P1498*3 (P0404, P0406)*4: Exhaust gas recirculation (EGR) system*1
P1259*3 (P2646, P2647)*4: VTEC system*1
*1:D17A2, D17A6 engine
*2:D17A6 engine
*3:'01-03 models
*4:'04 model
*5:'01 model
*6:'01-02 models
1. Check the fuel pressure.
Is the fuel pressure OK?
YES - Go to step 2.
NO - Check these items:
- If the pressure is too high, replace the fuel pressure regulator.
- If the pressure is too low, check the fuel pump, the fuel feed line, and the fuel filter, and replace 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. With the D17A1 or D17A2 engine, check the primary HO2S (Sensor 1) output with the HDS or a scan tool.
Is the output 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.
5. With a vacuum pump, apply vacuum to the evaporative emissions (EVAP) canister purge valve (A) from the intake manifold side.
Does the valve hold vacuum?
YES - Check the engine valve clearances and adjust if necessary (P0172 only). If the valve clearances are OK, replace the injectors.
NO - Replace the EVAP canister purge valve.