Ford F150 Pickup. Manual — 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