Ford F150 Pickup. Instruction - part 1405

B. Engine load 20-40 percent.  

C. Inferred catalyst temperature is 950-1300°F (510-704°C).  

D. Number of front O2 switches is 30.  

DTCs associated with this test are DTC P0420 (Bank No. 1 or Y-pipe system), and P0430 (Bank No. 2). 
Because an exponentially weighted moving average algorithm is used for malfunction determination, up to 6 
driving cycles may be required to illuminate MIL during normal customer driving. If KAM is reset or battery is 
disconnected, a malfunction will illuminate MIL in 2 drive cycles. 

General Catalyst Monitor Operation 

Monitor execution is once per drive cycle. Typical monitor duration is 700 seconds. In order for catalyst 
monitor to run, HO2S monitor must be complete and Secondary AIR and EVAP system functional with no 
stored DTCs. If catalyst monitor does not complete during a particular driving cycle, the already accumulated 
switch/signal data is retained in Keep Alive Memory (KAM) and is used during next driving cycle to allow 
catalyst monitor a better opportunity to complete. Rear HO2S can be located in various configurations to 
monitor different kinds of exhaust systems. In-line engines and many V-engines are monitored by their 
individual bank. A rear HO2S is used along with the front fuel control HO2S for each bank. These 2 sensors are 
used on an in-line engine; 4 sensors are used on a V-engine. Some V-engines have exhaust banks that combine 
into a single underbody catalyst. These systems are referred to as Y-pipe systems. They use only one rear HO2S 
along with 2 front, fuel-control HO2S. Y-pipe system uses 3 sensors in all. For Y-piped systems, 2 front HO2S 
signals are combined by PCM software to infer what HO2S signal would have been in front of monitored 
catalyst. Inferred front HO2S signal and the actual single rear HO2S signal is then used to calculate switch ratio.

Most vehicles that are part of Low Emission Vehicle (LEV) catalyst monitor phase-in will monitor less than 
100 percent of catalyst volume. Often this is the first catalyst brick of catalyst system. Partial volume 
monitoring is done on LEV and Ultra Low Emission Vehicle (ULEV) vehicles in order to meet the 1.75 
emission standard. Many applications that utilize partial-volume monitoring place rear HO2S sensor after first 
light-off catalyst housing, or after second catalyst housing in a 3-catalyst housing per bank system. A few 
applications place HO2S in middle of catalyst housing, between first and second bricks. 

Some 2003 model year Partial Zero Emission Vehicles (PZEV) will utilize three sets of HO2S's. The front 
sensors or stream 1 (HO2S11/HO2S21) are the primary fuel control sensors. The next sensors downstream or 
stream 2 in the exhaust are utilized to monitor the light-off catalyst (HO2S12/HO2S22). The last sensors 
downstream or stream 3 in the exhaust (HO2S13/HO2S23) are utilized for very long term fuel trim in order to 
optimize catalyst efficiency (For Aft Oxygen Sensor Control). For addition heated oxygen sensor information, 
see HEATED OXYGEN SENSOR MONITOR. 

Index ratios for Ethanol (Flex-fuel) vehicle vary based on the changing concentration of alcohol in fuel. The 
malfunction threshold typically increases as percentage of alcohol increases. For example, a malfunction 
threshold of 0.5 may be used at E10 (10 percent ethanol) and 0.9 may be used at E85 (85 percent ethanol). 
Malfunction thresholds are therefore adjusted based on percentage of alcohol in fuel. 

COMPREHENSIVE COMPONENT MONITOR 

Comprehensive Component Monitor (CCM) monitors for malfunctions in any powertrain electronic component 

 

2003 Ford Pickup F150 

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

  

or circuit that provides input or output signals to PCM that can affect emissions and is not monitored by another 
OBD-II monitor. Inputs and outputs are, at a minimum, monitored for circuit continuity or proper range of 
values. Where feasible, inputs are also checked for rationality, outputs are also checked for proper functionality. 
CCM covers many components and circuits and tests them in various ways depending on hardware, function, 
and type of signal. For example, analog inputs such as Throttle Position (TP) or Engine Coolant Temperature 
(ECT) are typically checked for opens, shorts and out-of-range values. This type of monitoring is performed 
continuously. Some digital inputs like Vehicle Speed (VS) or Crankshaft Position (CKP) rely on rationality 
checks; checking to see if input value makes sense at current engine operating conditions. These types of tests 
may require monitoring several components and can only be performed under appropriate test conditions. 
Outputs such as Idle Air Control (IAC) solenoid are checked for opens and shorts by monitoring a feedback 
circuit or "smart driver" associated with the output. Other outputs, such as relays, require additional feedback 
circuits to monitor secondary side of relay. Some outputs are also monitored for proper function by observing 
reaction of control system to a given change in output command. An IAC solenoid can be functionally tested by 
monitoring idle RPM relative to target idle RPM. Some tests can only be performed under appropriate test 
conditions. For example, transmission shift solenoids can only be tested when PCM commands a shift. 

The following is an example of some input and output components monitored by CCM. Components monitored 
may belong to engine, ignition, transmission, air conditioning, or any other PCM supported subsystem.  

Inputs 
 
Mass Air Flow (MAF) sensor, Intake Air Temperature (IAT) sensor, Engine Coolant Temperature (ECT) 
sensor, Throttle Position (TP) sensor, Camshaft Position (CMP) sensor, Air Conditioning Pressure Sensor 
(ACPS) and Fuel Tank Pressure (FTP) sensor. 

Outputs 
 
Fuel Pump (FP), Wide Open Throttle A/C Cutout (WAC), Idle Air Control (IAC), Shift Solenoid (SS), 
Torque Converter Clutch (TCC) solenoid, Intake Manifold Runner Control (IMRC), EVAP Canister 
Purge Valve, canister vent (CV) solenoid.  

CCM is enabled after engine starts and is running. A DTC is stored in Keep Alive Memory (KAM) and MIL is 
illuminated after 2 driving cycles when a malfunction is detected. Many CCM tests are also performed during 
KOEO and KOER self-tests. 

EVAPORATIVE EMISSION LEAK CHECK MONITOR 

Evaporative Emission (EVAP) Leak Check Monitor is an on-board strategy designed to detect a leak from a 
hole (opening) equal to or more than 0.040" (1.016 mm) in enhanced EVAP system. Proper function of 
individual components of enhanced EVAP system as well as its ability to flow fuel vapor to engine is also 
examined. EVAP leak check monitor relies on individual components of enhanced EVAP system to apply 
vacuum to fuel tank and then seal entire enhanced EVAP system from atmosphere. Fuel tank pressure is then 
monitored to determine total vacuum lost (bleed-up) for a calibrated period of time. Inputs from Engine Coolant 
Temperature (ECT) or Cylinder Head Temperature (CHT) sensor, Intake Air Temperature (IAT) sensor, Mass 
Air Flow (MAF) sensor, vehicle speed, Fuel Level Input (FLI) and Fuel Tank Pressure (FTP) sensor are 
required to enable EVAP Leak Check Monitor. 

 

2003 Ford Pickup F150 

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

  

EVAP Leak Check Monitor is executed by individual components of enhanced EVAP system as follows:  

1. EVAP canister purge valve function is to create a vacuum on fuel tank. A minimum duty cycle on EVAP 

canister purge valve (75 percent) must be met before EVAP Leak Check Monitor can begin.  

2. Canister Vent (CV) solenoid will close (100 percent duty cycle) with EVAP canister purge valve at its 

minimum duty cycle to seal enhanced EVAP system from atmosphere and obtain a target vacuum on fuel 
tank.  

3. Fuel Tank Pressure (FTP) sensor will be used by EVAP Leak Check Monitor to determine if target 

vacuum on fuel tank is being reached to perform leak check. Some vehicle applications with EVAP Leak 
Check Monitor use a remote in-line FTP sensor. Once target vacuum on fuel tank is achieved, change in 
fuel tank vacuum for a calibrated period of time will determine if a leak exists.  

4. If initial target vacuum cannot be reached, DTC P0455 (gross leak detected) will be set. EVAP Leak 

Check Monitor will abort and not continue with leak check portion of test. For some vehicle applications; 
if initial target vacuum cannot be reached after a refueling event and purge vapor flow is excessive, DTC 
P0457 (fuel cap off) is set. If initial target vacuum cannot be reached and purge flow is too small, DTC 
P1443 (no purge flow condition) is set. If initial target vacuum is exceeded, a system flow fault exists and 
DTC P1450 (unable to bleed-up fuel tank vacuum) is set. EVAP Leak Check Monitor will abort and not 
continue with leak check portion of test. 

If target vacuum is obtained on fuel tank, change in fuel tank vacuum (bleed-up) will be calculated for a 
calibrated period of time. Calculated change in fuel tank vacuum will be compared to a calibrated 
threshold for a leak from a hole (opening) of 0.040" (1.016 mm) in enhanced EVAP system. If calculated 
bleed-up is less than calibrated threshold, enhanced EVAP system passes. If calibrated bleed-up exceeds 
calibrated threshold, test will abort and rerun test up to 3 times. If bleed-up threshold is still being 
exceeded after 3 tests, a vapor generation check must be performed before DTC P0442 (small leak 
detected) will be set. This is accomplished by returning enhanced EVAP system to atmospheric pressure 
by closing EVAP canister purge valve and opening CV solenoid. Once FTP sensor observes fuel tank is 
at atmospheric pressure, CV solenoid closes and seals enhanced EVAP system. The fuel tank pressure 
build-up for a calibrated period of time will be compared to a calibrated threshold for pressure build-up 
due to vapor generation. If fuel tank pressure build-up exceeds threshold, leak test results are invalid due 
to vapor generation. EVAP Leak Check Monitor will attempt to retest again. If fuel tank pressure build-
up does not exceed threshold, leak test results are valid and DTC P0442 will be set. 

5. If the 0.40" (1.016 mm) test passes, test time is extended to allow 0.020" (0.508 mm) test to run. 

Calculated change in fuel tank vacuum over extended time is compared to a calibrated threshold for a 
leak from a 0.020" (0.508 mm) hole (opening). If calculated bleed-up exceeds calibrated threshold, vapor 
generation is run. If vapor generation passes (no vapor generation), an internal flag is set in PCM to run a 
0.020" (0.508 mm) test at idle (vehicle stopped). On the next start following a long engine off period, 

NOTE:

During EVAP Leak Check Monitor Repair Verification Drive Cycle, a PCM reset 
will bypass the minimum soak time required to complete monitor. See OBD-II 
DRIVE CYCLE DESCRIPTION under DRIVE CYCLES PROCEDURE. EVAP Leak 
Check Monitor will not run if key is turned off after a PCM reset. EVAP Leak 
Check Monitor will not run if a MAF sensor failure is indicated. EVAP Leak 
Check Monitor will not initiate until Heated Oxygen Sensor (HO2S) Monitor has 
completed.

 

2003 Ford Pickup F150 

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

  

enhanced EVAP system will be sealed and evacuated for first 10 minutes of operation. If appropriate 
conditions are met, a 0.020" (0.508 mm) leak check is conducted at idle. If test at idles fails, a DTC 
P0456 will be set. There is no vapor generation test with idle test. 

6. Malfunction Indicator Lamp (MIL) is activated for DTCs P0442, P0455, P0456, P0457, P1443 and 

P1450 (or P0446) after two occurrences of the same fault. The MIL can also be activated for any 
Enhanced EVAP system component DTCs in the same manner. The Enhanced EVAP system component 
DTCs P0443, P0452, P0453 and P1451 are tested as part of Comprehensive Component Monitor (CCM). 
For additional information, see COMPREHENSIVE COMPONENT MONITOR.  

EXHAUST GAS RECIRCULATION SYSTEM MONITOR - DIFFERENTIAL PRESSURE 
FEEDBACK EGR 

Differential Pressure Feedback EGR (DPFE) system monitor is an on-board strategy designed to test integrity 
and flow characteristics of EGR system. The monitor is activated during EGR system operation and after 
certain base engine conditions are satisfied. Input from ECT, CHT, IAT, TP and CKP sensors is required to 
activate EGR system monitor. Once activated, EGR system monitor will perform each test listed during engine 
modes and conditions indicated. Some EGR system monitor tests are also performed during KOEO or KOER 
self-test:  

1. DPFE sensor and circuit are continuously tested for opens and shorts. The monitor looks for DPFE circuit 

voltage to exceed maximum or minimum allowable limits. DTCs associated with this test are DTCs 
P0405 and P0406.  

2. EGR vacuum regulator solenoid is continuously tested for opens and shorts. The monitor looks for an 

EGR Vacuum Regulator (EGRVR) circuit voltage that is inconsistent with EGRVR circuit commanded 
output state. DTC associated with this test is DTC P0403.  

3. Test for a stuck open EGR valve or EGR flow at idle is continuously performed whenever at idle (TP 

sensor indicating closed throttle). The monitor compares DPFE circuit voltage at idle to DPFE circuit 
voltage stored during KOEO self-test to determine if EGR flow is present at idle. DTC associated with 
this test is DTC P0402.  

4. DPFE sensor upstream hose is tested once per drive cycle for disconnect and plugging. The test is 

performed with EGR valve closed and during a period of acceleration. PCM will momentarily command 
EGR valve closed. The monitor looks for DPFE sensor voltage to be inconsistent for a no flow voltage. A 
voltage increase or decrease during acceleration while EGR valve is closed may indicate a fault with 
signal hose during this test. DTC associated with this test is DTC P1405.  

5. EGR flow rate test is performed during a steady state when engine speed and load are moderate and EGR 

vacuum regulator duty cycle is high. The monitor compares DPFE circuit voltage to a desired EGR flow 
voltage for that state to determine if EGR flow rate is acceptable or insufficient. This is a system test and 
may trigger a DTC for any fault causing EGR system to fail. DTC associated with this test is DTC P0401. 
DTC P1408 is similar to P0401, but performed during KOER self-test conditions.  

6. The MIL is activated after one of the above tests fails on 2 consecutive drive cycles.  

NOTE:

If the vapor generation is high on some vehicle Enhanced EVAP Systems, 
where the monitor does not pass, the result is treated as a no test. 
Thereby, the test is complete for the day.

 

2003 Ford Pickup F150 

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