DTC P0172 [YF (2.0L Zetec)]

id0102d0818500

DTC P0172

Fuel system too rich

DETECTION CONDITION

• The fuel adaptive strategy continuously monitors fuel delivery hardware. If the adaptive fuel table for reach a lean calibrated limit, the PCM determines that the system to rich.

POSSIBLE CAUSE

• Fuel system malfunction
• Excessive fuel pressure
• Leaking/contaminated fuel injectors
• Leakage fuel pressure regulator
• Low fuel pressure or running out of fuel
• Vapor recovery system
• Intake-air system
- Air leaks after the MAF
- Vacuum leaks
- PCV system
- Improperly seated engine dipstick
• EGR system
- Leaking gasket
- Stuck EGR valve
- Leaking diaphragm or EVR
• Base engine
- Oil overfill
- Cam timing
- Cylinder compression
- Exhaust leaks before or near the HO2S-11

Diagnostic procedure

Warning
• Read the following warnings before performing the fuel system services:
- Fuel vapor is hazardous. It can easily ignite, causing serious injuries and damage. Always keep sparks and flames away from fuel.
- Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" decided in this manual.
Caution
• Disconnecting/connecting quick release connector without cleaning it may possibly cause damage to fuel pipe and quick release connector. Always clean quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign materials.

STEP

INSPECTION

ACTION

1
VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
• Has FREEZE FRAME DATA been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2
VERIFY REPAIR INFORMATION AVAILABILITY
• Verify related service repair information availability.
• Is any related repair information available?
Yes
Perform repair or diagnosis according to the available repair information.
If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
INDETIFY TRIGGER DTC FOR FREEZE FRAME DATA
• Is DTC P0172 on FREEZE FRAME DATA?
Yes
Go to the next step.
No
Go to FREEZE FRAME DATA DTC inspection.
4
PERFORM VISUAL INSPECTION
Note
• It is necessary to address all Continuous Memory Ignition and Misfire DTCs, if received during Continuous Memory testing, before addressing any Fuel Trim DTCs.
• Check visually for following:
- Intake-air for leaks, obstructions and damage.
- Air cleaner element, air cleaner housing for blockage.
- Integrity of the PCV system
- Vacuum leaks
• Were any concerns found during inspection?
Yes
Repair or replace malfunctioning part, then go to Step 30.
No
Go to the next step.
5
CHECK CONDITIONS RELATED TO MAF SENSOR
Note
• Most weather service reports are a local barometric pressure that has been corrected to sea level. However, the BARO PID reports the actual barometric pressure for altitude the vehicle is being diagnosed in Local weather conditions (high or low pressure areas) will change the local barometric pressure by several inches of mercury [+/- 3 Hz. (+/- 1 in.Hg.)].
• Verify the MAF sensor is connector. If not, repair as necessary.
• Connect the WDS or equivalent to DLC-2.
• Start the engine.
• Access the BARO, LONGFT1 and MAF V PIDs on fully warmed-up engine.
• Check that the BARO PID is approximately the same as the barometric pressure reading for the location, day and altitude the vehicle is being diagnosed at.
- BARO PID values in PCM memory require updating at high throttle openings. If vehicle is driven down from higher altitudes for diagnosing, complete three or four heavy accelerations at greater than half-throttle to allow BARO PID to update.
- BARO PID must be within +/- 6Hz. (+/- 2 in.Hg.) of the altitude value in Barometric Pressure Reference Chart (at Training Manual).
- Make BARO PID comparisons to Barometric Pressure Reference Chart or diary airport barometric pressure reports, if available.
• Check that the LONGFT1 and PID at idle is not more negative than -12%.
• Check that the MAF V PID at idle and neutral is not greater then 30% of the normal MAF V listed in Section 01-40, Reference values (or not greater than 1.1 V).
• Are two of the above three check normal?
Yes
Go to Step 7.
No
Go to the next step.
6
CHECK TO ISOLATE MAF SENSOR FROM LEAN DELIVEABILITY OCCURRENCE
Note
• Due to increasingly stringent emission/OBD requirements, a fuel system DTC on some vehicles will be generated without a noticeable drivability concern with or without MAF sensor disconnected. Under these conditions, if the BARO, LONGFT1 and MAF V PID indicates a MAF sensor concern, replace the MAF sensor.
• Disconnect MAF sensor.
• Start the engine.
• Drive the vehicle.
• Is the lean drivability symptom (lack of power, spark knock/detonation, back/jerk or hesitation/surge on acceleration) gone?
Yes
Replace MAF sensor, then go to Step 30.
No
Go to the next step.
7
PERFORM KOER SELF TEST
• Disconnect fuel vapor hose from intake manifold and plug fitting at intake manifold.
• Connect the WDS or equivalent to DLC-2.
• Start the engine and run at 2,000 rpm for 5 minutes and return to idle.
• Complete Key On Engine Running (KOER) self test.
• Are any HO2S DTCs P1131 or P1132 present?
Yes

DTC P1130 and P1131 displayed:

Go to the next step.

DTC P1130 and P1132 displayed:

Go to Step 14.
No
Go to Step 17.
8
HO2S-11 CIRCUIT TEST (WITH LEAN DTCS)
• Disconnect HO2S-11.
• Connect the WDS or equivalent to DLC-2.
• Turn the ignition switch to ON.
•  Access O2S11 PID.
Note
• If arcing occurs (including a short), remove jumper wire and go to Step 12 (check fuse in the heater circuit).
• Jumper the HO2S-11 terminal 4 and 1 at the harness side connector.
• Is O2S11 PID reading 1.30 V or greater?
Yes
Inspect for circuit between HO2S-11 terminal 3 and PCM terminal 91.
Then go to the next step.
No
Go to Step 11.
9
CHECK SIGNAL RETURN CIRCUIT FOR OPEN
• Measure resistance between HO2S-11 harness side connector terminal 3 and the battery negative post.
• Is resistance reading less than 5.0 ohms?
Yes
Go to Step 17.
No
Go to the next step.
10
CHECK HO2S-11 SIGNAL RETURN CIRCUIT FOR OPEN IN HARNESS
• Disconnect PCM.
• Measure resistance between HO2S-11 terminal 3 and PCM terminal 91 at harness side connector.
• Is resistance reading less than 5.0 ohms?
Yes
Replace PCM, then go to Step 30.
No
Replace open circuit, then go to Step 30.
11
CHECK HO2S-11 SIGNAL AND HO2S-11 GND CIRCUIT FOR OPEN IN HARNESS
• Disconnect PCM.
• Measure resistance between HO2S-11 terminal 4 and PCM terminal 60 at harness side connector.
• Is resistance reading less than 5.0 ohms?
Yes
Go to the next step.
No
Replace open circuit, then go to Step 30.
12
CHECK HO2S-11 SIGNAL CIRCUIT FOR SHORT TO GND IN HARNESS
• Disconnect PCM.
• Measure resistance following at PCM harness side connector.
- Between terminal 60 and 24, 51, 76, 103
- Between terminal 60 and 91
• Is each resistance greater than 10,000 ohms?
Yes
Go to the next step.
No
Replace for short to GND circuit, then go to Step 30.
13
CHECK HO2S-11 SIGNAL CIRCUIT FOR SHORT TO GND IN THE SENSOR
• Disconnect PCM.
• Reconnect HO2S-11.
• Measure resistance following at PCM harness side connector.
- Between terminal 60 and 24, 51, 76, 103
- Between terminal 60 and 91
• Is each resistance greater than 10,000 ohms?
Yes
Replace PCM, then go to Step 30.
No
Replace HO2S-11, then go to Step 30.
14
HO2S-11 CIRCUIT CHECK (FOR RICH DTCS)
• Disconnect HO2S-11.
• Connect the WDS or equivalent to DLC-2.
• Turn the ignition switch to ON.
• Access O2S11 PID.
• Is the reading 0.2 V or less?
Yes
Go to the next step.
No
Go to Step 16.
15
CHECK HO2S-11 CIRCUIT FOR SHORT TO VPWR AND HO2S-11 HEATER GND IN HARNESS
• Disconnect PCM.
• Measure resistance following at PCM harness side connector.
- Between terminal 60 and 71,97
- Between terminal 60 and 93
• Is each resistance greater than 10,000 ohms?
Yes
Replace PCM, then go to Step 30.
No
Repair for short circuit, then go to the next step.
16
CHECK HO2S-11 SIGNAL FOR SHORT TO HO2S-11 HEATER CIRCUIT IN THE SENSOR
• HO2S-11 disconnected.
• Measure resistance between terminal 3 and 4 at HO2S-11 component side connector.
• Is the resistance greater than 10,000 ohms?
Yes
Go to the next step.
No
Replace HO2S-11, then go to Step 30.
17
CHECK FUEL PRESSURE
• Install the fuel pressure gauge.
• Connect the WDS or equivalent to DLC-2.
• Turn the ignition switch to ON.
• Turn the fuel pump to on using the PID FP on simulation function.
Note
•  The fuel pump will only operate for approximately 8 s when simulation function is selected and activated.
•  Is the fuel pressure within with range for the vehicle being diagnosed?
Yes
Go to the next step.
No
Go to Step 23.
18
CHECK INJECTOR FAULT PIDS AND ASSOCIATED DTCS
•  Access INJ1F, INJ2F, INJ3F and INJ4F PIDs.
Note
•  If misfire DTCs are present, access only injector fault PIDs corresponding to misfire DTCs.
•  Is DTC P0201 through P0204 or an injector (s) fault present?
Yes
Go to the next step.
No
Go to Step 22.
19
CHECK FUEL INJECTOR (S) AND HARNESS RESISTANCE
Note
• This causes Continuous Memory DTCs.
• Disconnected PCM.
Note
• Use the fuel injector fault PID to determine the fuel injector circuit (s) requiring testing.
• Measure resistance following for malfunctioning injector in Step 18 at PCM harness side connector.
- Between 70 and 71, 97 (INJ1F, P0201)
- Between 96 and 71, 97 (INJ2F, P0202)
- Between 20 and 71, 97 (INJ3F, P0203)
- Between 95 and 71, 97 (INJ4F, P0204)
• Is the resistance between 11.0-18.0 ohms?
Yes
Replace PCM, then go to Step 30.
No
Go to the next step.
20
CHECK FUEL INJECTOR HARNESS RESISTANCE
• Disconnect the malfunctioning fuel injector in Step 18.
• Measure the resistance for following at harness side connector:
- Between fuel injector No.1 terminal 2 and PCM terminal 71, 97 (INJ1F, P0201)
- Between fuel injector No.1 terminal 1 and PCM terminal 70 (INJ1F, P0201)
- Between fuel injector No.2 terminal 2 and PCM terminal 71, 97 (INJ2F, P0202)
- Between fuel injector No.2 terminal 1 and PCM terminal 96 (INJ2F, P0202)
- Between fuel injector No.3 terminal 2 and PCM terminal 71, 97 (INJ3F, P0203)
- Between fuel injector No.3 terminal 1 and PCM terminal 20 (INJ3F, P0203)
- Between fuel injector No.4 terminal 2 and PCM terminal 71, 97 (INJ4F, P0204)
- Between fuel injector No.4 terminal 2 and PCM terminal 95 (INJ4F, P0204)
• Is each resistance less than 5.0 ohms?
Yes
Go to the next step.
No
Repair for open circuit, then go to Step 30.
21
CHECK FUEL INJECTOR HARNESS CIRCUIT FOR SHORT TO POWER AND GROUND
• Disconnect PCM.
• Malfunctioning fuel injector in Step 18 disconnected.
• Measure resistance for following at PCM harness side connector.
- Terminal 70 and 71, 97 (INJ1F, P0201)
- Terminal 70 and 24, 51, 76, 103 (INJ1F, P0201)
- Terminal 96 and 71, 97 (INJ2F, P0202)
- Terminal 96 and 24, 51, 76, 103 (INJ2F, P0202)
- Terminal 20 and 71, 97 (INJ3F, P0203)
- Terminal 20 and 24, 51, 76, 103 (INJ3F, P0203)
- Terminal 95 and 71, 97 (INJ4F, P0204)
- Terminal 95 and 24, 51, 76, 103 (INJ4F, P0204)
• Is each resistance greater than 10,000 ohms?
Yes
Go to the next step.
No
Repair for short circuit, then go to Step 30.
22
INSPECT FUEL INJECTOR (S)
• Inspect fuel injectors.
• Are fuel injectors normal?
Yes
Intermittent malfunction exist, go to the Step 30.
No
Replace suspected fuel injector, then go to Step 30.
23
CHECK SYSTEM INTEGRITY
• Visually inspect the following complete fuel delivery system for damage, leaks, looseness, cracks, kinks, pinching, or abrasion caused by a collision or mishandling;
• Are fuel injectors normal?
- Fuel line
- Fuel line connection
- Relays
- Fuel tank
- Fuel pump
- Fuel pressure regulator
- Pulsation damper
- Fuel injector
• Visually inspect electrical harness and connectors for loose pins, corrosion, abrasion, or other damage from collision or mishandling.
• Check electrical connectors for proper mating.
• Verify vehicle has followed maintenance schedule.
• Verify inertia fuel shutoff (IFS) switch is set.
• Verify battery is fully charged (12.5 V or higher).
• Verify electrical/fuse integrity.
• Verify fuel level in the tank is sufficient.
• Are any concerns present?
Yes
Repair or replace malfunctioning part, then go to Step 30.
No
Go to the next step.
24
CHECK VOLTAGE AT FUEL PUMP HARNESS CONNECTOR
• Follow the IFS switch reset procedure.
• Connect battery charger.
• Verify IFS switch state.
• Connect the WDS or equivalent to DLC-2.
• Disconnect the fuel pump harness connector at the fuel pump.
• Turn the ignition switch to ON.
• Access FP PID.
• Connect a digital multimeter between the fuel pump terminal 1 and 3 at fuel pump harness side connector.
• Measure voltage during fuel pump operates using simulation function FP PID.
• Is the voltage greater than 12.5 V?
Yes
Go to the next step.
No
Inspect for following circuit.
• Between fuel pump terminal 1 and IFS switch terminal 2
• Between fuel pump terminal 3 and body GND
• Between IFS switch terminal 1 and fuel pump relay terminal 87
Then go to Step 30.
25
CHECK FUEL FILTER FOR PROPER MAINTENANCE
• Locate and inspect the vehicle maintenance schedule and fuel filter.
• Check for last repair date.
• Was the fuel filter replaced with the last scheduled maintenance interval?
Yes
Go to the next step.
No
Replace fuel filter, then go to Step 30.
26
CHECK FUEL PRESSURE
• Install the fuel pressure gauge.
• Release the fuel pressure.
• Turn the ignition switch to ON.
• Access FP PID.
• Run the fuel pump to obtain maximum fuel pressure using simulation function FP PID.
Note
• The fuel pump will only operate for approximately 8 s when simulation function is selected and activate.
• Is the fuel pressure within the specified pressure range?
Yes
Go to Step 29.
No

Greater than 448 kPa:

Replace fuel pressure regulator in fuel tank, then go to Step 30.

Less than 310 kPa:

Go to the next step.
27
CHECK PRESSURE REGULATOR AND PULSATION DAMPER DIAPHAGM
• Fuel pressure gauge installed.
• Start the engine and run it for 10 s.
• Stop the engine and wait 10 s.
• Start the engine and run it for 10 s.
• Stop the engine and remove the vacuum hose from pulsation damper port.
• Inspect for fuel in the vacuum hose or pulsation damper.
• Is fuel present in the vacuum hose or pulse damper?
Yes
Replace the pulsation damper, then go to Step 30.
No
Go to the next step.
28
CHECK FUEL SUPPLY LINE FOR RESTRICTION
• Disconnect fuel supply line at the fuel rail.
• Disconnect fuel supply line at the fuel pump.
• Check the fuel supply line for restrictions due to blockage, kinking or pinching.
• Apply 21 to 34 kPa regulated shop air pressure to the fuel supply line.
• Does air flow freely through the line?
Yes
Replace the fuel pump unit, then go to Step 30.
No
Repair or replace for fuel line, then go to Step 30.
29
CHECK FUEL INJECTOR
• Perform the FUEL INJECTOR INSPECTION.
• Are fuel injectors normal?
Yes
Intermittent malfunction exist, go to the next step.
No
Replace malfunctioning fuel injector, then go to the next step.
30
VERIFY TROUBLESHOOTING OF DTC P0172 COMPLETED
• Make sure to reconnect all disconnected connectors.
• Clear the DTC from the PCM memory using the WDS or equivalent.
• Drive vehicle for following and repeat this 3 times:
- From a stop, accelerate to 104 km/h {65 MPH}.
- Decelerate at closed throttle until 64 km/h {40 MPH} (no brakes).
• Is the PENDING CODE same DTC present?
Yes
Replace PCM, then go to the next step.
No
Go to the next step.
31
VERIFY AFTER REPAIR PROCEDURE
• Perform "After Repair Procedure".
• Is there any DTC present?
Yes
Go to the applicable DTC inspection.
No
Troubleshooting completed.