DTC P0172 - System Too Rich (Bank 1) -

WARNING: This page is about a different variant/trim than selected.

DTC DETECTING CONDITION:
- Two consecutive driving cycles with malfunction
TROUBLE SYMPTOM:
- Erroneous idling
- Engine stalls.
- Poor driving performance
CAUTION: After repair or replacement of malfunctioning parts, conduct Clear Memory Mode < Ref. to OPERATION , CLEAR MEMORY MODE > and INSPECTION MODE < Ref. to OPERATION , INSPECTION MODE. >

DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK ANY OTHER DTC ON DISPLAY.	Is any other DTC displayed?	Inspect the relevant DTC using "List of Diagnostic Trouble Code (DTC)". < Ref. to LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . >	Go to step 2.
2 CHECK EXHAUST SYSTEM.	Are there holes or loose bolts on exhaust system?	Repair exhaust system.	Go to step 3.
3 CHECK EGR VALVE.	Is EGR valve clogged?	Replace EGR valve.	Go to step 4.
4 CHECK AIR INTAKE SYSTEM.	Are there holes, loose bolts or disconnection of hose on air intake system?	Repair air intake system.	Go to step 5.
5 CHECK PURGE CONTROL SOLENOID VALVE.	Is purge control solenoid valve clogged?	Replace purge control solenoid valve.	Go to step 6.
6 CHECK PCV VALVE.	Is PCV valve clogged?	Replace PCV valve.	Go to step 7.
7 CHECK FUEL PRESSURE. WARNING: Place "NO FIRE" signs near the working area. Be careful not to spill fuel on the floor. Release fuel pressure. Disconnect connector from fuel pump relay. Start the engine and run it until it stalls. After the engine stalls, crank it for five more seconds. Turn ignition switch to OFF. Connect connector to fuel pump relay. Disconnect fuel delivery hose from fuel filter, and connect fuel pressure gauge. Install fuel filler cap. Start the engine and idle while gear position is neutral. Measure fuel pressure while disconnecting pressure regulator vacuum hose from intake manifold. WARNING: Before removing fuel pressure gauge, release fuel pressure. NOTE: If fuel pressure does not increase, squeeze fuel return hose 2 to 3 times, then measure fuel pressure again.	Is the measured value within 284 to 314 kPa (2.9 to 3.2 kg/ cm² , 41 to 46 psi)?	Go to step 8.	Repair the following items. Fuel pressure too high Clogged fuel return line or bent hose Fuel pressure too low Improper fuel pump discharge Clogged fuel supply line
8 CHECK FUEL PRESSURE. After connecting pressure regulator vacuum hose, measure fuel pressure. WARNING: Before removing fuel pressure gauge, release fuel pressure. NOTE: If fuel pressure does not increase, squeeze fuel return hose 2 to 3 times, then measure fuel pressure again. If out of specification as measured at this step, check or replace pressure regulator and pressure regulator vacuum hose.	Is the measured value within 206 to 235 kPa (2.1 to 2.4 kg/ cm² , 30 to 34 psi)?	Go to step 9.	Repair the following items. Fuel pressure too high Malfunctioning pressure regulator Clogged fuel return line or bent hose Fuel pressure too low Malfunctioning pressure regulator Improper fuel pump discharge Clogged fuel supply line
9 CHECK ENGINE COOLANT TEMPERATURE SENSOR. Start the engine and warm-up completely. Read data of engine coolant temperature sensor signal using Subaru Select Monitor or general scan tool. NOTE: Subaru Select Monitor For detailed operation procedure, refer to the "READ CURRENT DATA FOR ENGINE". < Ref. to SUBARU SELECT MONITOR . > General scan tool For detailed operation procedures, refer to the General Scan Tool Instruction Manual.	Is the measured value within 70 to 100°C (158 to 212°F)?	Go to step 10 .	Replace engine coolant temperature sensor. < Ref. to ENGINE COOLANT TEMPERATURE SENSOR . >
10 CHECK INTAKE MANIFOLD PRESSURE SENSOR SIGNAL. Start the engine and warm-up engine until coolant temperature is greater than 60°C (140°F). Place the selector lever in "N" or "P" position. Turn A/C switch to OFF. Turn all accessory switches to OFF. Read data of intake manifold pressure sensor signal using Subaru Select Monitor or general scan tool. NOTE: Subaru Select Monitor For detailed operation procedure, refer to the "READ CURRENT DATA FOR ENGINE". < Ref. to SUBARU SELECT MONITOR . > General scan tool For detailed operation procedures, refer to the General Scan Tool Instruction Manual.	Is the measured value within 24.0 to 41.3 kPa (180 to 310 mmHg, 7.09 to 12.20 inHg) when idling or within 73.3 to 106.6 kPa (550 to 800 mmHg, 21.65 to 31.50 inHg) when turning ignition switch ON?	Contact with SOA service center. NOTE: Inspection by DTM is required, because probable cause is deterioration of multiple parts.	Replace intake air temperature and pressure sensor. < Ref. to PRESSURE SENSOR . >