P0172
DTC P0172: Fuel System Too RichSpecial Tools Required
Vacuum pump/gauge, 0 - 30 in.Hg, Snap-on YA4000A or equivalent, commercially available
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
P0134, P0135 (P1166, P1167)*: A/F sensor (Sensor 1) heater
P0137, P0138: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S (Sensor 2) heater
P1021, P1026: Valve pause system
P0401, P0406, P1491 (P1498)*: Exhaust gas recirculation (EGR) system
*: 2003 ULEV model
1. Check the fuel pressure.
Is the fuel pressure OK?
YES -
- Go to step 2 (ULEV model).
- Check the valve clearances and adjust if necessary. If the valve clearances are OK, replace the injectors (AT-PZEV (SULEV) model).
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 pipe, and the fuel filter, and replace the fuel pressure regulator.
2. Turn the ignition switch OFF.
3. Disconnect the vacuum hose (A), and connect a vacuum pump/gauge, 0 - 30 in.Hg, to the hose from the evaporative emission (EVAP) canister side.
4. Apply vacuum to the hose.
Does it hold vacuum?
YES - Check the valve clearances and adjust if necessary. If the valve clearances are OK, replace the injectors.
NO - Replace the EVAP canister purge valve.