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Randall    (Cheeko)
Randall (Cheeko), Certified Mechanic Ford Motor Co.
Category: Ford
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Experience:  18 years as a Ford tech and still going
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I have a PO133 and PO 153 I have replaced all o2 sensors ...

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I have a PO133 and PO 153 I have replaced all o2 sensors air idler control plugs and wires do you know what else I can do.


    DTC/HO2S Reference List:

    • DTC P0133 = HO2S-11
    • DTC P0153 = HO2S-21

Key on, engine off.

Select Generic OBD II Function from the menu and trigger.

Press Continue.

Select Diagnostic Monitoring Test Results from the menu and trigger.

Scroll to Test ID: 01 trigger and press start.

Key off.

Is the indicated value greater than the minimum threshold?
Yes No
CLEAR the DTCs. COMPLETE HO2S Monitor Drive Cycle (REFER to Section 2, GO to H20 . If test results indicate a pass, testing is complete. GO to H23 .


    Fuel calculations can be affected by unmetered air leaks.

Carefully inspect the following areas for potential air leaks:

Hoses connecting to MAF sensor assembly.

Hoses connecting to throttle body.

Intake manifold gasket leaks.

PCV disconnected.

Vacuum lines disconnected.

Improperly seated engine oil dipstick, tube, and oil fill cap.

Exhaust leaks at flanges and gaskets.

Are any air leaks present?
Yes No
REPAIR source of air leak. CLEAR the DTCs. COMPLETE HO2S Monitor Drive Cycle GO to H24 .


    Note: Refer to the PCM connector pin number in the beginning of this pinpoint test.

Disconnect suspect HO2S.

Check for water contamination.

Jumper HO2S signal to VPWR at the HO2S harness connector.

Key on, engine off.

Note: HO2S displayed as O2S on Scan Tool.

Access the correct HO2S PID.

Note: If viewing the HO2S11 (O2S11) PID on the 2.3L Focus, the engine must be running.

Is the voltage greater than 1.50 volts?
Yes No
KEY OFF. REPLACE HO2S. CHANGE oil/filter. CLEAR the DTCs. COMPLETE HO2S Monitor Drive Cycle KEY OFF. REMOVE jumper wire. GO to H25 .


Note: Refer to the PCM harness connector pin numbers in the beginning of this pinpoint test.

Note: On some applications, a vehicle hoist is required to access the HO2S harness.

Visually inspect the HO2S circuit for exposed wiring, water contamination, corrosion and proper assembly.

Disconnect PCM.

Measure resistance of HO2S SIG circuit between PCM harness connector pin and HO2S harness connector.

Measure resistance of HO2S SIG RTN circuit between PCM harness connector pin and HO2S harness connector.

Is the resistance less than 5.0 ohms?
Yes No
GO to H26 . REPAIR open circuit. COMPLETE HO2S Monitor Drive Cycle


Measure resistance between the HO2S SIG and VPWR circuit at the PCM harness connector pin.

Is the resistance greater than 10,000 ohms?
Yes No
GO to H27 . GO to H28 .


Investigate the following items as potential sources of HO2S contamination:

Use of unapproved silicon sealers.

Fuel contaminated by silicon additives.

Excessive oil burning (i.e. rings, valve seals and oil overfill).

Glycol (antifreeze) leaking internally in the engine.

Lead contaminated fuel.

Short drive cycles in cold weather.

Use of unapproved cleaning agents.

Were any of the above conditions or concerns found during inspection?
Yes No
REPAIR source of contamination. REPLACE HO2S and oil/filter. CLEAR the DTCs. COMPLETE HO2S Monitor Drive Cycle If diagnosing DTC P0141 or P0161, GO to H30 . All others: REPLACE PCM.


    Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Measure resistance of the HO2S SIG circuit and HO2S Signal Return circuit between the PCM harness connector pin and the HO2S harness connector.

Is the resistance less than 5.0 ohms?
Yes No
REPLACE HO2S. REPAIR as necessary.


Drive Cycles Description of OBD II Drive Cycle

The following procedure is designed to execute and complete the OBDII monitors and to clear the Ford P1000, I/M readiness code. To complete a specific monitor for repair verification, follow steps 1 through 4, then continue with the step described by the appropriate monitor found under the "OBDII Monitor Exercised" column. When the ambient air temperature is outside 4.4 to 37.8°C (40 to 100 °F), or the altitude is above 2438 meters (8000 feet), the EVAP monitor will not run. If the P1000 code must be cleared in these conditions, the PCM must detect them once (twice on some applications) before the EVAP monitor can be "bypassed" and the P1000 cleared. The EVAP "bypassing" procedure is described in the following drive cycle.

The OBDII Drive Cycle will be performed using a scan tool. Consult the instruction manual for each described function

Drive Cycle Recommendations

Most OBDII monitors will complete more readily using a "steady foot" driving style during cruise or acceleration modes. Operating the throttle in a "smooth" fashion will minimize the time required for monitor completion.

Fuel tank level should be between 1/2 and 3/4 fill with 3/4 fill being the most desirable.

The Evaporative Monitor can only operate during the first 30 minutes of engine operation. When executing the procedure for this monitor, stay in part throttle mode and drive in a smooth fashion to minimize "fuel slosh".


For best result, follow each of the following steps as accurately as possible:

OBDII Monitor ExercisedDrive Cycle ProcedurePurpose of Drive Cycle Procedure
Drive Cycle Preparation1. Install scan tool. Turn key on with the engine off. Cycle key off, then on. Select appropriate Vehicle & Engine qualifier. Clear the continuous diagnostic trouble codes (DTCs) and reset the emission monitors information in the powertrain control module (PCM).Bypass engine soak timer. Resets OBDII Monitor status.
2. Begin to monitor the following PIDs: ECT, EVAPDC, FLI (if available) and TP MODE. Start vehicle WITHOUT returning to Key Off.
3. Idle vehicle forXXXXXat 64 Km/h (40 MPH) until ECT is at least 76.7°C (170°F).
Prep for Monitor Entry4. Is IAT within 4.4 to 37.8°C (40 to 100°F)? If not, complete the following steps, but note that step 14 will be required to "bypass" the EVAP monitor and clear the P1000.Engine warm-up and provide IAT input to the PCM.
HEGO5. Cruise at 64 Km/h (40 MPH) for at least 5 minutes.Executes the HEGO monitor.
EVAP6. Cruise at 64 to 128 Km/h (45 to 65 MPH) for 10 minutes (avoid sharp turns and hills). NOTE: To initiate the monitor TP MODE should = PT, EVAPDC must be > 75%, and FLI must be between 15 and 85%.Executes the EVAP monitor (If IAT is within 4.4 to 40°C (40 to 120°F).
Catalyst7. Drive in stop-and-go traffic conditions. Include five different constant cruise speeds, ranging from 32 to 112 Km/h (20 to 70 MPH) over a 10 minute period.Executes the Catalyst Monitor.
EGR8. From a stop, accelerate to 72 Km/h (45 MPH) at 1/2 to 3/4 throttle. Repeat 3 times.Executes the EGR Monitor.
SEC AIR/CCM (Engine)9. Bring the vehicle to a stop. Idle with transmission in drive (neutral for M/T) for 2 minutes.Executes the ISC portion of the CCM.
CCM (Trans)10. For M/T, accelerate from 0 to 80 Km/h (0 to 50 MPH), continue to step 11. For A/T, from a stop and in overdrive, moderately accelerate to 80 Km/h (50 MPH) and cruise for at least 15 seconds. Stop vehicle and repeat without overdrive to 64 Km/h (40 MPH) cruising for at least 30 seconds. While at 64 Km/h (40 MPH), activate overdrive and accelerate to 80 Km/h (50 MPH) and cruise for at least 15 seconds. Stop for at least 20 seconds and repeat step 10 five times.Executes the transmission portion of the CCM.
Misfire & Fuel Monitors11. From a stop, accelerate to 104 Km/h (65 MPH). Decelerate at closed throttle until 64 Km/h (40 MPH) (no brakes). Repeat this 3 times.Allows learning for the misfire monitor.
Readiness Check12. Access the On-Board System Readiness (OBDII monitor status) function on the scan tool. Determine whether all non-continuous monitors have completed. If not, go to step 13.Determines if any monitor has not completed.
Pending Code Check and EVAP Monitor "Bypass" Check13. With the scan tool, check for pending codes. Conduct normal repair procedures for any pending code concern. Otherwise, rerun any incomplete monitor. If the EVAP monitor is not complete AND IAT was out of the 4.4 to 37.8 °C (40 to 100 °F) temperature range in step #4, or the altitude is over 2438 m. (8000 ft.), the EVAP "bypass" procedure must be followed. Proceed to Step 14.Determines if a pending code is preventing the clearing of P1000.
EVAP Monitor "Bypass"14. Park vehicle for a minimum of 8 hours. Repeat steps 2 through 12. DO NOT REPEAT STEP 1.Allow the "bypass" counter to increment to two.

Hi you will need a scanner and run done the problem you have using the pinpoint test provided if you don't have one I recommend that you take it to a repair shop that does to find the problem without a scanner it will be hard to dianois . you will be just throwing parts at it thanks

Randall (Cheeko) and 5 other Ford Specialists are ready to help you
Customer: replied 9 years ago.
Reply to Cheeko's Post: I have done all that you sent but I still have these codes. I am not really sure where to go from here
HiCustomer Thank you for asking your question on Just Answer. The other experts and I are working on your answer. By the way, it would help us to know:

-What year is your Ford?
-What model is your Ford?
-How many miles are on your Ford?
-What type of engine is in your Ford?
-What have you already tried?

Thank you again for trusting us with your problem. Please reply as soon as possible so that we can finish answering your question.

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