Test Procedure

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2005 Mercury Sable, 2005 Mercury Mountaineer, 2005 Mercury Monterey, 2005 Mercury Montego, and 2005 Mercury Mariner. 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	Setting Condition	Testing
P0104	KOER	DC4
P0104	Continuous Memory	DC1
P1101	KOEO	DC6
P1101	KOER	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 DC20.	All other continuous memory DTCs: DISREGARD the current diagnostic trouble code (DTC) at this time. DIAGNOSE the next DTC. GO to POWERTRAIN DTC CHARTS AND DESCRIPTIONS - GASOLINE MODELS .

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. Check throttle body bore for sludge. Verify the MAF sensor is connected. Repair as necessary.

Are 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. Charge the battery as necessary, then remove the ventilation system and properly vent to the 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.	Key in OFF position.
GO to PINPOINT TEST Z STEP 1 .	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 MAF HARNESS

NOTE: For vehicles with a stand alone MAF sensor (IAT sensor not internal to the MAF sensor), disregard the MAF circuit checks to the 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 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
GO to DC12.	REPAIR the open circuit.

DC12 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.

DC13 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 DC14.	INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) .

DC14 CHECK THE MAF CIRCUIT VOLTAGE CYCLING INTEGRITY

Diagnostic tool connector connected.
Key ON, engine OFF.
Access the PCM and monitor 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 when the VPWR jumper is removed?

Yes	No
Key in OFF position. REMOVE the jumper wires. If OK, INSTALL a new MAF sensor. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .	Key in OFF position. REMOVE the jumper wires. GO to DC15.

DC15 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 DC16.	REPAIR the open circuit.

DC16 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 DC17.	REPAIR the open circuit.

DC17 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. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) .	REPAIR the open circuit.

DC18 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 idle is not stable, refer to SYMPTOM CHARTS - GASOLINE MODELS .
Run the engine up to 1, 500 RPM for 5 seconds, then bring it back to idle. 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, INSTALL a new MAF sensor. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .	GO to DC19.

DC19 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.

DC20 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 DC21.

DC21 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 DC22.	GO to DC24.

DC22 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 wires. CHECK the MAF sensor electrical connector for damage, corrosion, and water ingress. If OK, INSTALL a new MAF sensor. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .	Key in OFF position. GO to DC23.

DC23 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 DC25.	Key in OFF position. REPAIR the short circuit to PWR.

DC24 CHECK THE MAF 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 DC22.

DC25 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. The concern is elsewhere. RETURN to SYMPTOM CHARTS - GASOLINE MODELS for further direction.	INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) .

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

Is a concern present?

Yes	No
REPAIR as necessary. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .	GO to DC27.

DC27 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 include 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 diagnosis, 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 - GASOLINE MODELS (or not greater than 1.3 volts).

Are the PID values within the expected ranges?

Yes	No
GO to DC29.	GO to DC28.

DC28 CHECK TO ISOLATE MAF SENSOR FROM LEAN DRIVEABILITY OCCURRENCE

Due to increasingly stringent emission/OBD 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.
Key in OFF position.
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
If OK, INSTALL a new MAF/IAT sensor. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .	GO to DC29.

DC29 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
Unable to duplicate or identify the fault at this time. GO to Pinpoint Test Z .	The concern is elsewhere. RETURN to SYMPTOM CHARTS - GASOLINE MODELS for further direction.