Test Procedure

WARNING: This page does not describe the selected car, but rather 30 other vehicles, including the 2004 Mercury Sable, 2004 Mercury Mountaineer, 2004 Mercury Monterey, 2004 Mercury Marauder, and 2004 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Proceed to DTC testing steps listed in FAULT CODE SETTING CONDITION table of fault code setting condition.

FAULT CODE SETTING CONDITION

Fault Code	KOEO	KOER	Continuous Memory
P0102	DC4	DC4	DC4
P0103	DC19	DC19	DC19
P0104		DC4	DC1
P1100	DC17	DC17	DC17
P1101	DC6	DC1

DC1 DTC P1101: CHECK FOR MAF SENSOR CONTINUOUS MEMORY DTCS

Retrieve CMDTCs.

Is a continuous memory MAF DTC present with the KOER DTC P1101?

Yes	No
GO to DC2.	Key in OFF position. GO to DC4.

DC2 VERIFY CONTINUOUS MEMORY DTC P0102

Is a continuous memory DTC P0102 present with the KOER DTC P1101?

Yes	No
GO to DC4.	GO to DC3.

DC3 VERIFY CONTINUOUS MEMORY DTC P0103

Is a continuous memory DTC P0103 present with the KOER DTC P1101?

Yes	No
GO to DC19.	All other continuous memory DTCs: DISREGARD the current diagnostic trouble code (DTC) at this time. DIAGNOSE the next DTC. GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS .

DC4 KOER AND CONTINUOUS MEMORY DTCS P0102, P0104 OR P1101: CHECK THE INTAKE AIR SYSTEM FOR LEAKS, OBSTRUCTIONS AND DAMAGE

CHECK the air inlet system (air cleaner, housing, ductwork) for obstructions or blockage.
CHECK for broken/loose air outlet tube clamps (throttle body and air cleaner assembly ends), cracks/holes in the air outlet tube, and worn gaskets between the MAF sensor and the air cleaner assembly. Verify the MAF sensor is connected. Repair as necessary.

Were there any concerns found during the visual inspection?

Yes	No
Key in OFF position. Repair as necessary.	GO to DC5.

DC5 CHECK THE MAF PID

Run the engine up to 1,500 RPM for 5 seconds, then bring it back to idle.
Access the PCM and monitor the MAF V PID.

Is the voltage less than 0.23 V?

Yes	No
Key in OFF position. GO to DC8.	Key in OFF position. GO to DC6.

DC6 CHECK THE MAF SIGNAL SENT TO THE PCM

NOTE: DTC P1101 can be generated by a low charged vehicle battery or the garage exhaust ventilation system. Repair battery as necessary, then remove the ventilation system and properly vent to outside atmosphere. Check the air inlet system (air cleaner, housing, ductwork) for obstructions or blockage. Rerun the KOEO self-test.

MAF/IAT Sensor connector connected.
Key ON, engine OFF.
Access the PCM and monitor the MAF V PID.

Is the voltage less than 0.2 V?

Yes	No
GO to DC7.	Key in OFF position. GO to DC8.

DC7 CHECK THE MAF SIGNAL SENT TO THE PCM

Key ON, engine running.
Access the PCM and monitor the MAF V PID.

Is the voltage between 0.46 - 2.44 V?

Yes	No
Unable to identify the concern at this time. GO to PINPOINT TEST Z STEP 1.	Key in OFF position. GO to DC8.

DC8 CHECK THE VPWR TO THE MAF SENSOR

MAF/IAT Sensor connector disconnected.
Key ON, engine OFF.
Measure the voltage between:

( + )MAF/IAT Sensor Connector, Harness Side	( - ) Vehicle Battery
VPWR	Negative terminal

Is the voltage greater than 10.5 V?

Yes	No
GO to DC9.	Key in OFF position. REPAIR the open circuit.

DC9 CHECK THE PWRGND CIRCUIT TO MAF SENSOR

Measure the voltage between:

( + )Vehicle Battery	( - ) MAF/IAT Sensor Connector, Harness Side
Positive terminal	PWRGND

Is the voltage greater than 10.5 V?

Yes	No
Key in OFF position. GO to DC10.	Key in OFF position. REPAIR the open circuit.

DC10 CHECK FOR SHORTS BETWEEN CIRCUITS IN THE MAF HARNESS

NOTE: For vehicles with a stand alone MAF sensor (IAT not internal to MAF), disregard MAF circuit checks to IAT and SIGRTN.

MAF/IAT Sensor connector disconnected.
PCM connector disconnected.
Measure the resistance between:

( + )MAF/IAT Sensor Connector, Harness Side	( - ) MAF/IAT Sensor Connector, Harness Side
MAF	PWRGND
MAF	MAF RTN
MAF	SIGRTN
MAF	IAT

Are the resistances greater than 10K ohms?

Yes	No
GO to DC11.	REPAIR the short circuit.

DC11 CHECK THE MAF RTN CIRCUIT FOR A SHORT TO PWRGND IN THE HARNESS

Measure the resistance between:

( + )MAF/IAT Sensor Connector, Harness Side	( - ) MAF/IAT Sensor Connector, Harness Side
MAF RTN	PWRGND

Is the resistance greater than 10K ohms?

Yes	No
GO to DC13.	REPAIR the short circuit to GND.

DC12 CHECK THE MAF CIRCUIT FOR A SHORT TO PWRGND IN THE PCM

PCM connector connected.
Measure the resistance between:

( + )MAF/IAT Sensor Connector, Harness Side	( - ) MAF/IAT Sensor Connector, Harness Side
MAF	PWRGND

Is the resistance greater than 10K ohms?

Yes	No
GO to DC13.	INSTALL a new PCM.

DC13 CHECK THE MAF CIRCUIT VOLTAGE CYCLING INTEGRITY

Diagnostic tool connector connected.
Key ON, engine OFF.
Access the MAF V PID.
Connect a 5 amp fused jumper wire between the following:

Point A MAF/IAT Sensor Connector, Harness Side	Point B MAF/IAT Sensor Connector, Harness Side
MAF RTN	PWRGND
MAF	VPWR

Take the PID reading while both jumpers are installed.
Remove the VPWR jumper while observing the MAF V PID.

Does the MAF V PID change from greater than 4.50 volts to less than 0.26 volt (closer to zero volt) when the VPWR jumper is removed?

Yes	No
Key in OFF position. INSTALL a new MAF sensor. REMOVE the jumper wire(s). RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .	Key in OFF position. REMOVE the jumper wire(s). GO to DC14.

DC14 CHECK THE MAF CIRCUIT FOR AN OPEN IN THE HARNESS

PCM connector disconnected.
Measure the resistance between:

( + )PCM Connector, Harness Side	( - ) MAF/IAT Sensor Connector, Harness Side
MAF	MAF

Is the resistance less than 5 ohms?

Yes	No
GO to DC15.	REPAIR the open circuit.

DC15 CHECK THE PWRGND CIRCUIT FOR AN OPEN IN THE HARNESS

PCM connector disconnected.
Measure the resistance between:

( + )MAF/IAT Sensor Connector, Harness Side	( - ) Vehicle Battery
PWRGND	Negative terminal

Is the resistance less than 5 ohms?

Yes	No
GO to DC16.	REPAIR the open circuit.

DC16 CHECK THE MAF RTN CIRCUIT FOR AN OPEN IN THE HARNESS

Measure the resistance between:

( + )PCM Connector, Harness Side	( - ) MAF/IAT Sensor Connector, Harness Side
MAF RTN	MAF RTN

Is the resistance less than 5 ohms?

Yes	No
INSTALL a new PCM.	REPAIR the open circuit.

DC17 DTC P1100: CHECK THE MAF CIRCUIT FOR INTERMITTENT VOLTAGE TO THE PCM

CHECK for broken/loose air outlet tube clamps (throttle body and air cleaner assembly ends), cracks/holes in the air outlet tube, and worn gaskets between the MAF sensor and the air cleaner assembly. Verify the MAF sensor is connected.
Key ON, engine running.
Access the PCM and monitor the MAF V PID.
If the idle is not stable, GO to SYMPTOM CHARTS - CNG, FLEX-FUEL & GASOLINE .
Run the engine up to 1,500 RPM for 5 seconds, then bring it back to idle.
Access the PCM and monitor the MAF V PID.
Lightly tap on the MAF sensor and wiggle the harness connector to simulate road shock.

Does the MAF PID go below 0.23 volt or above 4.6 volts?

Yes	No
Key in OFF position. INSPECT the MAF sensor connector. If OK, REPLACE the MAF sensor. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .	GO to DC18.

DC18 CHECK THE MAF CIRCUIT FOR AN INTERMITTENT OPEN OR SHORTS

Key ON, engine running.
Access the PCM and monitor the MAF V PID.
Wiggle, shake, and bend small sections of the wiring harness while working from the sensor to the PCM.

Does the MAF PID go below 0.23 volt or above 4.6 volts?

Yes	No
Key in OFF position. REPAIR as necessary. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .	Key in OFF position. Unable to duplicate or identify the fault at this time.

DC19 DTC P0103: CHECK THE MAF SENSOR SCREEN FOR CONTAMINATION

NOTE: DTC P0103 can be generated by foreign material blocking the MAF sensor screen, causing an air flow restriction.

CHECK the MAF sensor screen for contamination or blockage.
CHECK the air cleaner element and air tubes for proper installation and sealing.

Were any problems found?

Yes	No
Repair as necessary. Rerun Self Test.	GO to DC20.

DC20 DTC P0103: CHECK THE MAF SENSOR SIGNAL HIGH INPUT TO THE PCM

Key ON, engine OFF.
Access the PCM and monitor the MAF V PID.

Is the voltage greater than 2.44 V?

Yes	No
Key in OFF position. GO to DC21.	GO to DC23.

DC21 CHECK THE MAF SENSOR SIGNAL SENT TO THE PCM

MAF/IAT Sensor connector disconnected.
Connect a 5 amp fused jumper wire between the following:

Point A MAF/IAT Sensor Connector, Harness Side	Point B MAF/IAT Sensor Connector, Harness Side
MAF RTN	PWRGND

Key ON, engine OFF.
Access the PCM and monitor the MAF V PID.

Is the voltage less than 0.1 V?

Yes	No
Key in OFF position. Remove the jumper wire(s). CHECK the MAF sensor electrical connector for damage, corrosion, and water ingress. If ok, replace MAF sensor. Reset KAM.	Key in OFF position. GO to DC22.

DC22 CHECK THE MAF CIRCUIT FOR A SHORT TO VOLTAGE

PCM connector disconnected.
Key ON, engine OFF.
Measure the voltage between:

( + )PCM Connector, Harness Side	( - )
MAF	Ground

Is the voltage less than 1 V?

Yes	No
GO to DC24.	Key in OFF position. REPAIR the short circuit to PWR.

DC23 CHECK THE MAF SENSOR SIGNAL SENT TO THE PCM

Key ON, engine running.
Monitor the MAF signal voltage while increasing the engine RPM from idle to approximately 2,500 RPM, and then back to idle.
Access the PCM and monitor the MAF V PID.

Is the voltage between 0.23 - 4.6 V?

Yes	No
Key in OFF position. Intermittent concern. GO to PINPOINT TEST Z STEP 1.	Key in OFF position. GO to DC21.

DC24 VERIFY THE IDLE CONCERN

PCM connector connected.
MAF/IAT Sensor connector connected.
Key ON, engine running.

Is there an idle concern present?

Yes	No
Disregard DTC P0103 at this time. RETURN to SYMPTOM CHARTS - CNG, FLEX-FUEL & GASOLINE .	INSTALL a new PCM.

DC25 DTC P0171, P0172, P0174, P0175, P1131, P1132, P1151, P1152, P1130, P1150, P2195, P2196, P2197, P2198: (OR LEAN DRIVEABILITY CONCERNS) CHECK CONDITIONS RELATED TO THE MAF SENSOR

CHECK the air inlet system (air cleaner, housing, ductwork) for obstructions or blockage.
CHECK for broken/loose air outlet tube clamps (throttle body and air cleaner assembly ends), cracks/holes in the air outlet tube, and worn gaskets between the MAF sensor and the air cleaner assembly. Verify the MAF sensor is connected.

Were any problems found?

Yes	No
Repair as required and reset KAM.	GO to DC26.

DC26 DTC P0171, P0172, P0174, P0175, P1131, P1132, P1151, P1152, P1130, P1150, P2195, P2196, P2197, P2198: (OR LEAN DRIVEABILITY CONCERNS) CHECK CONDITIONS RELATED TO THE MAF SENSOR

NOTE: Most weather reports are a local barometric pressure that has been corrected to sea level. However, the BARO PID reports the actual barometric pressure for the altitude where the vehicle is being diagnosed. Local weather conditions (high or low pressure areas) will change the local barometric pressure by several inches of mercury.

NOTE: The BARO PID values in Keep Alive Memory require updating at high throttle openings. If the vehicle is driven down from higher altitudes for diagnosing, carry out 3 or 4 heavy accelerations at greater than half-throttle to allow the BARO PID to update. Make BARO PID comparisons to the BAROMETRIC PRESSURE REFERENCE CHART or hourly airport barometric pressure or altimeter reports, if available. The BARO PID must be within +/ - 6 Hz. (+/- 2 in Hg.) of the altitude value in BAROMETRIC PRESSURE REFERENCE CHART (at the beginning of this pinpoint test).

NOTE: A MAF V PID value of less than 0.6 volt may indicate an incorrectly installed air cleaner or a leak in the air inlet system.

Key ON, engine running.
Allow the engine to stabilize at the correct operating temperature.
Access the PCM and monitor the LONGFT1, LONGFT2, MAF V and BARO PIDs.
Carry out the following diagnostic checks:
- Check that the BARO PID is approximately the same as the barometric pressure reading for the location, day, and altitude where the vehicle is being diagnosed.
- Check that the MAF V PID at idle and neutral is not greater than 30% of the normal MAF V listed in REFERENCE VALUES - CNG, FLEX-FUEL & GASOLINE (or not greater than 1.3 volts).

Are the PID values within the expected ranges?

Yes	No
GO to DC28.	Key in OFF position. GO to DC27.

DC27 CHECK TO ISOLATE MAF SENSOR FROM LEAN DRIVEABILITY OCCURRENCE

Due to increasingly stringent emission/OBD2 requirements, a fuel system DTC on some vehicles can be generated without a noticeable driveability concern with or without the MAF sensor disconnected. Under these conditions, if the BARO_V, LONGFT1, LONGFT2 and MAF PIDs indicate a MAF sensor concern, install a new MAF sensor.
MAF/IAT Sensor connector disconnected.
Key ON, engine running.
Drive the vehicle on the road.

Is the lean driveability symptom (lack of power, spark knock/detonation, buck/jerk or hesitation/surge on acceleration) gone?

Yes	No
INSTALL a new MAF/IAT sensor. Reset KAM.	GO to DC28.

DC28 VERIFY THE DTC

Are any of the following DTCs present: P0171, P0172, P0174, P0175, P1130, P1131, P1132, P1150, P1151, P1152, P2195, P2196, P2197 or P2198?

Yes	No
GO to DC29.	The concern is elsewhere. RETURN to SYMPTOM CHARTS - CNG, FLEX-FUEL & GASOLINE for further direction.

DC29 VERIFY THE TYPE OF VEHICLE

Is this a natural gas vehicle?

Yes	No
For DTCs P0171, P0172, P0174, P0175, P1130 and P1150 GO to PINPOINT TEST HA STEP 13. For DTCs P1131, P1151, P2195 and P2197 GO to PINPOINT TEST HA STEP 30. For DTCs P1132, P1152, P2196 and P2198 GO to PINPOINT TEST HA STEP 41.	Unable to duplicate or identify the fault at this time. GO to PINPOINT TEST Z STEP 1.