Test Procedure

H1 CHECK FOR DTCS

Are DTCs P0171, P0172, P2195, P2196 or P219A present?

Yes	No
GO to H2.	RETURN to SYMPTOM CHARTS for further direction.

H2 RICH OR LEAN SYSTEM DTCS

NOTE: Do not clear the DTCs or reset the keep alive memory (KAM).

Access the PCM and record the CHT PID from the freeze frame data. The freeze frame data is used to recreate the concern.
Carry out the PCM self-test.

Are any DTCs present other than P0171, P0172, P2195, P2196 or P219A?

Yes	No
RETURN to SYMPTOM CHARTS for further direction.	GO to H3.

H3 CARRY OUT A VISUAL INSPECTION ON THE INTAKE AIR SYSTEM AND ALL VACUUM HOSES

Ignition OFF.
Check the air filter element and housing for blockage.
Inspect the entire air intake system for leaks such as:
- hoses connecting to the MAF sensor assembly
- cracked or punctured intake air tube
- loose connections on the intake air tube at the air cleaner housing or throttle body
- hoses connecting to the throttle body
- obstructions, restrictions, or damage
Check the throttle plate for obstructions or sludge.
Inspect the entire length of all vacuum hoses for:
- correct connections
- damage or cracks
- damaged or cracked vacuum tees
Inspect the intake manifold or gaskets for leaks.
Inspect the exhaust gas recirculation (EGR) system for leaks such as:
- EGR valve gasket leak to the intake manifold
Verify the integrity of the positive crankcase ventilation (PCV) system.
Verify the correct PCV valve part number.
Inspect the exhaust system for leaks at flanges and gaskets.
Visually inspect the HO2S for:
- pinched, shorted, and corroded wiring or pins
- oil or water contamination
- crossed sensor wires
Inspect for an incorrectly seated oil dipstick, dipstick tube, or oil fill cap.

Is a concern present?

Yes	No
For vacuum leak concerns, GO to H4. For all others, REPAIR as necessary. Clear the PCM DTCs. REPEAT the self-test.	GO to H4.

H4 CHECK FOR THE PRESENCE OF A VACUUM LEAK

NOTE: Fuel trim values at idle are more sensitive to a vacuum leak. The vacuum leak (unmetered air) represents a larger portion of the total air flow at idle than at part throttle.

NOTE: The barometric pressure (BARO) PID is not a recommended PID to monitor when diagnosing a vacuum leak. Barometric pressure is calculated during high engine load, when the vacuum leak represents a small portion of the total air flow.

NOTE: When calculating the total fuel correction in the following steps, if LONGFT1 equals +13% and SHRTFT1 equals +23%, the total fuel correction for bank 1 equals +36%. If LONGFT1 equals +24% and SHRTFT1 equals -3% the total fuel correction for bank 1 equals +21%.

NOTE: Stabilize the engine at the temperature recorded by the freeze frame CHT PID. If the freeze frame CHT PID is not available, maintain the engine coolant temperature between 82°C - 101°C (180°F - 215°F) and the intake air temperature less than 46°C (115°F).

Ignition ON, engine running.
Access the PCM and monitor the ECT (TEMP), CHT (TEMP) and IAT (TEMP) PIDs.
Access the PCM and monitor the LONGFT1 (PER) and SHRTFT1 (PER) PIDs.
Allow the engine to stabilize at the temperature necessary to recreate the concern.
Mathematically add and record the LONGFT PID value to the SHRTFT PID value, for a total fuel correction at idle.
Increase the engine speed to 2, 500 RPM for 10 seconds.
Record the LONGFT1 and SHRTFT1 PID values.
Mathematically add and record the LONGFT PID value to the SHRTFT PID value, for a total fuel correction at 2, 500 RPM.

Is the total fuel correction value difference, between idle and 2, 500 RPM, less than 15 percent?

Yes	No
No vacuum leak is present. GO to H7.	GO to H5.

H5 LOCATE THE VACUUM LEAK

NOTE: Do not clamp or pinch a hard plastic hose. Use a vacuum cap or equivalent to restrict the hose.

NOTE: Restricting the EVAP vapor hose while the EVAP emission canister is purging may shift the SHRTFT. Carry out a visual inspection as necessary.

NOTE: When monitoring for a decrease in the SHRTFT1 PID in the following steps, if SHRTFT1 is +15%, but when the hose is restricted SHRTFT1 decreases to -7%, the decrease in the SHRTFT1 PID equals 22%.

Locate the vacuum tees for the intake air and PCV systems.
Access the PCM and monitor the SHRTFT1 (PER) PID.
Restrict the vacuum lines one at a time for 30 seconds. If a vacuum leak is present, the SHRTFT1 PID value decreases as the hose is restricted.

Is the decrease in the SHRTFT1 PID greater than 15 percent when one of the vacuum hoses is restricted?

Yes	No
GO to H6.	INSPECT the intake air system for a vacuum leak in the intake manifold or intake gaskets. REPAIR as necessary. For repair verification, GO to H6.

H6 VACUUM LEAK REPAIR VERIFICATION

Access the PCM and monitor the SHRTFT1 (PER) PID.
Allow the engine to stabilize at the temperature necessary to recreate the concern.
Record the SHRTFT1 PID value.
Ignition OFF.
Repair the vacuum leak.
Ignition ON, engine running.
Allow the engine to stabilize at the temperature necessary to recreate the concern.
Access the PCM and monitor the SHRTFT1 (PER) PID.
Compare the recorded SHRTFT1 PID value, prior to the vacuum leak repair, to the current SHRTFT1 PID value.

Is the decrease in the SHRTFT1 PID greater than 15 percent?

Yes	No
RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .	A vacuum leak is still present. GO to H5.

H7 CHECK THE FUEL PRESSURE

WARNING: BEFORE WORKING ON OR DISCONNECTING ANY OF THE FUEL TUBES OR FUEL SYSTEM COMPONENTS, RELIEVE THE FUEL SYSTEM PRESSURE TO PREVENT ACCIDENTAL SPRAYING OF FUEL. FUEL IN THE FUEL SYSTEM REMAINS UNDER HIGH PRESSURE, EVEN WHEN THE ENGINE IS NOT RUNNING. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN SERIOUS PERSONAL INJURY.

Ignition OFF.
Carry out the fuel system pressure test. Refer to the Fuel System article for the Fuel System Pressure Test procedure.

Is the ignition ON, engine OFF fuel system pressure between 331 - 485 kPa (48 - 70 psi)?

Yes	No
GO to H8.	GO to PINPOINT TEST HC .

H8 CHECK THE FUEL SYSTEM FOR PRESSURE STABILITY - FAST LEAKDOWN

NOTE: When the fuel pump is commanded off, the fuel pressure may substantially decrease and then stabilize.

NOTE: During output state control, the fuel pump stays commanded on only for approximately 5 seconds.

Ignition OFF.
Ignition ON, engine OFF.
Access the PCM and control the FP (MODE) PID.
Run the fuel pump to obtain maximum fuel pressure.
Command the fuel pump off.
Allow the fuel pressure to stabilize.
Record the stabilized reading.
Monitor the fuel pressure for 10 seconds.

Does the fuel pressure remain within 34 kPa (5 psi) of the recorded reading after 10 seconds?

Yes	No
GO to H9.	GO to PINPOINT TEST HC .

H9 CHECK THE FUEL SYSTEM FOR PRESSURE STABILITY - SLOW LEAKDOWN

Continue to monitor the fuel pressure for 1 minute.

Does the fuel pressure remain within 34 kPa (5 psi) of the recorded reading after 1 minute?

Yes	No
For DTC P219A, UNABLE to duplicate or identify the concern at this time. GO to PINPOINT TEST Z . For all others, GO to H10.	GO to HC8.

H10 CHECK THE SEPARATION LEVEL OF THE ETHANOL/WATER MIXTURE AND GASOLINE IN THE FUEL

NOTE: This step requires the use of a locally obtained 200 ml beaker and a 25 ml graduated cylinder.

NOTE: After approximately 3 minutes of standing, the ethanol and water mixes together and settles to the bottom of the 25 ml graduated cylinder. The gasoline rises to the top.

Fill the 200 ml beaker with 5 ml of clean water.
Use the pressure relief valve on the mechanical fuel gauge to drain 22 ml of fuel into an approved clean container.
Pour 20 ml of fuel from the approved clean container into the 25 ml graduated cylinder.
Add enough water from the 200 ml beaker to the 25 ml graduated cylinder to bring the total volume of liquid to 24 ml.
Insert a stopper plug in the opening of the 25 ml graduated cylinder.
Firmly hold the stopper in place and shake the 25 ml graduated cylinder to mix the water and fuel.
Allow the liquid to stand and separate for approximately 3 minutes.
Record the separation level from the 25 ml graduated cylinder where the ethanol/water mixture and gasoline meet.

Did the ethanol/water mixture and gasoline separate?

Yes	No
GO to H11.	The ethanol/water mixture separates from the gasoline. If the fuel does not appear to separate, then the fuel is either 100% ethanol or a mixture of ethanol and water. REPLACE the contaminated fuel. Clear the PCM DTCs. REPEAT the self-test.

H11 CALCULATE THE PERCENTAGE OF ETHANOL IN THE FUEL

NOTE: Use the illustration as an example for calculating the percentage of ethanol in the following steps. If the separation level is at 14 ml the calculation becomes; 14 minus 4, then multiply by 5 to equal 50. The percentage of ethanol in the fuel is 50%.

Ignition OFF.
Take the recorded separation level from the previous step and subtract the amount of water added.

Multiply the new value by 5. This new value is the percentage of ethanol in the fuel.

Courtesy of FORD MOTOR CO.

Item Number	Description
1	Stopper
2	Gasoline
3	Separation Point at 14 ml
4	Ethanol/Water Mixture

Record the calculated percentage of ethanol in the fuel.

Is the calculated percentage of ethanol in the fuel less than 25%?

Yes	No
For DTCs P0171 or P2195, GO to HC9. For all others, GO to H12.	REPAIR as necessary. ADVISE the customer of the correct fuel type required for this vehicle. REFER to the Owner's Literature for additional information. Clear the PCM DTCs. REPEAT the self-test.

H12 CHECK FOR A STUCK OPEN EVAP PURGE VALVE

Disconnect the fuel vapor to EVAP purge valve line at the EVAP purge valve.
Connect a vacuum gauge to the EVAP purge valve hose connection at the EVAP purge valve.
Evaporative Emission (EVAP) Purge Valve connector disconnected.
Ignition ON, engine running.

Is any vacuum present at the EVAP purge valve connection?

Yes	No
INSTALL a new Evaporative Emission (EVAP) Purge valve. REFER to the Evaporative Emissions article. Clear the PCM DTCs. REPEAT the self-test.	GO to H13.

H13 CHECK THE UNIVERSAL HO2S ACTIVITY

Ignition ON, engine running.
Access the PCM and monitor the FUELSYS (MODE) PID.
Allow the engine to enter closed loop fuel control.
Access the PCM and monitor the O2S11_CUR (CUR) PID.

Does the O2S11_CUR PID value switch?

Yes	No
Unable to duplicate or identify the concern at this time. GO to PINPOINT TEST Z .	GO to H14.

H14 CHECK THE UO2SPC CIRCUIT FOR AN OPEN

Ignition OFF.
Universal HO2S-Front connector disconnected.
PCM connector disconnected.

Measure the resistance between:

(+) Universal HO2S-Front Connector, Harness Side	(-) PCM Connector, Harness Side
UO2SPC11 - Pin 1	UO2SPC11 - Pin E8

Is the resistance less than 5 ohms?

Yes	No
INSTALL a new Universal HO2S. REFER to the Electronic Engine Controls article. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) . REPEAT the self-test.	REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test.