Ford F150 Pickup. Instruction - part 1496

Fig. 232: Locating HO2S (V6 Or V8 With Single Exhaust) 
Courtesy of FORD MOTOR CO. 

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

Fig. 233: Identifying HO2S Connector Terminals 
Courtesy of FORD MOTOR CO. 

Testing 

20) For Continuous Memory Only DTCs P0133 Or P0153: Perform KOER Self-Test 
DTC P0133 or P0153 are set during self-test when frequency and amplitude fall below a calibrated limit 
in HO2S as follows: 

z

DTC P0133 is for HO2S-11. See Fig. 230-Fig. 232 .  

z

DTC P0153 is for HO2S-21. See Fig. 231 or Fig. 232 .  

Possible causes are:  

z

HO2S Sensor Contaminated  

z

Exhaust Leaks  

z

Open Or Shorted Circuit  

z

Improper Fueling  

z

Faulty MAF Sensor  

z

Deteriorating HO2S Sensor  

NOTE:

Test procedure begins with step 20). No test procedures have been omitted.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

z

Leak In Air Induction System  

Perform KOER ON-DEMAND SELF-TEST under QUICK TEST. If either DTC P0040, P0041, P1127, 
P1128, P1129 or P2278 is present, go to appropriate system test. See DIAGNOSTIC TROUBLE CODE 
DEFINITIONS. If DTC P0040, P0041, P1127, P1128, P1129 or P2278 are not present, go to next step. 

21) DTC P0133 & P0153: HO2S Response Test 
 
Turn ignition switch to ON position. Using scan tool, access GENERIC OBD-II FUNCTIONS. Press 
CONTINUE. Select DIAGNOSTIC MONITORING TEST RESULTS from menu and press enter. Scroll 
to TEST ID: 01 trigger and press start. Press START. Turn ignition switch to OFF position. 

If measured value is less than minimum threshold, go to step 23). If measured value is more than 
minimum threshold, fault cannot be identified at this time. Perform PCM RESET PROCEDURE under 
CLEARING CODES under SELF-DIAGNOSTIC SYSTEM. Perform DRIVE CYCLES. Ensure HO2S 
MONITOR PROCEDURE is performed. Repeat step 20). If no DTCs are present, testing is complete. 

23) Check For Unmetered Air Leaks 
 
Fuel calculations can be affected by unmetered air (vacuum) leaks. Check the following as potential 
source of air leak: 

z

Hoses Connected To MAF Sensor Or Throttle Body Leaking  

z

Intake Manifold Gasket Leaking  

z

PCV System Disconnected  

z

Vacuum Lines Disconnected  

z

Poorly Seated Oil Dip Stick &/Or Dipstick Tube Or Cap  

z

Exhaust Leaks At Flanges Or Gaskets  

If none of these conditions are present, go to next step. If any of these conditions are present, repair 
source of air leak as necessary. Perform PCM RESET PROCEDURE under CLEARING CODES under 
SELF-DIAGNOSTIC SYSTEM. Perform DRIVE CYCLES. Ensure HO2S MONITOR PROCEDURE 
is performed. 

24) Check HO2S Circuit Wiring 
Turn ignition switch to OFF position. Disconnect suspect HO2S harness connector. Check for water 

NOTE:

For additional information on HO2S testing with scan tool, see TESTING 
under HEATED OXYGEN SENSOR MONITOR under DIAGNOSTIC 
MONITORING TESTS.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 21) to step 23). No test procedures have been omitted.

NOTE:

HO2S may be displayed as O2S on scan tool.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

contamination. Clean and repair as necessary. Connect a jumper wire between HO2S SIG and VPWR 
circuits at suspect HO2S harness connector. See Fig. 233. Turn ignition switch to ON position. Using 
scan tool, access appropriate HO2S PID (11, 12, 21 or 22) from PID/DATA MONITOR & RECORD 
menu. If HO2S PID voltage is 1.5 volts or less, turn ignition switch to OFF position, remove jumper wire 
and go to next step. If HO2S PID voltage is more than 1.5 volts, replace faulty HO2S. Change engine oil 
and filter. Perform PCM RESET PROCEDURE under CLEARING CODES under SELF-
DIAGNOSTIC SYSTEM. Perform DRIVE CYCLES. Ensure HO2S MONITOR PROCEDURE is 
performed. 

25) Check HO2S SIG Or SIG RTN Circuits For Open 
Turn ignition switch to OFF position. Disconnect suspect HO2S connector and PCM connector(s). 
Inspect connectors for loose, damaged or corroded terminals. Check HO2S circuit for exposed wiring, 
water contamination, corrosion and proper assembly. Repair as necessary. Using a DVOM, measure 
resistance of suspect HO2S SIG and SIG RTN circuits between PCM harness connector and HO2S 
harness connector. See PCM HO2S, PWR GND & VPWR CIRCUIT TERMINAL 
IDENTIFICATION table. See Fig. 233. If both resistance measurements are less than 5 ohms, go to 
next step. If either resistance measurement is 5 ohms or more, repair open in HO2S SIG or SIG RTN 
circuit. Perform DRIVE CYCLES. Ensure HO2S MONITOR PROCEDURE is performed. 

PCM HO2S, PWR GND & VPWR CIRCUIT TERMINAL IDENTIFICATION 

26) Check HO2S SIG Circuit For Short To VPWR 
 
Using a DVOM, measure resistance between HO2S SIG and VPWR circuits at PCM harness connector. 
See PCM HO2S, PWR GND & VPWR CIRCUIT TERMINAL IDENTIFICATION table. See PCM 
CONNECTOR IDENTIFICATION. If resistance measurement is more than 10 k/ohms, go to next 
step. If resistance measurement is 10 k/ohms or less, go to step 28). 

27) For Continuous Memory Only DTCs P0131 & P0151: Check For Source Of Potential HO2S 
Contamination 
The HO2S sensor is monitored for a negative voltage known as Characteristic Shift Downward (CSD). If 

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

HO2S 
Location

104-Pin PCM Terminal 

No.

122-Pin PCM Terminal 

No.

150-Pin PCM Terminal

No.

HO2S-11

60

B26

E45

HTR-11

93

B21

E7

HO2S-12

35

T3

T28

HTR-12

95

T21

T15

HO2S-21

87

B27

E44

HTR-21

94

B20

E8

HO2S-22

61

T2

T29

HTR-22

96

T29

T16

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline