refer to bank No. 1. DTCs P0174 (lean) and P0175 (rich) refer to bank No. 2. Possible causes for these
faults are:
z
Fuel System
Excessive fuel pressure, leaking or contaminated fuel injectors, leaking fuel pressure regulator, low
fuel pressure or engine running out of fuel or vapory recovery system fault.
z
Induction System
Air leaks after MAF sensor, air intake system obstructions, vacuum leaks, PCV system or
improperly seated engine oil dipstick.
z
EGR System
Leaking gasket, stuck EGR valve or leaking diaphragm or EVR.
z
Engine Mechanical
Engine oil overfilled, cam timing, cylinder compression or exhaust leaks before or near HO2S.
Inspect engine for obvious defects in specified systems. Repair as necessary. If no faults are found, go to
TEST DC, step 25).
42) Perform KOER Self-Test
Perform KOER ON-DEMAND SELF-TEST. If KOER DTC P1131, P1132, P1151, P1152 P2195,
P2196, P2197 or P2198 is present, go to next step. If none of these DTCs are present, proceed as follows:
z
For Continuous Memory DTCs P0171, P0172, P0174, P0175, P1130 or P1150, go to next step.
z
For any other DTCs, fault may be intermittent. Go to TEST Z, step 1).
43) Check Fuel Pressure
Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Install Natural
Gas Fuel Rail Pressure Gauge Tool Kit (134-00114) to fuel rail Schrader valve. Using scan tool, access
FRP PID (if available) from PID/DATA MONITOR & RECORD menu. With ignition switch turned to
ON position, record FRP sensor PID or fuel pressure gauge reading. Start engine and allow to idle. Again
WARNING:
Fuel system remains under high pressure even when engine is not
running. To avoid injury, release fuel pressure before disconnecting
any fuel system hose or component. See FUEL SYSTEM PRESSURE
RELEASE procedure under FUEL SYSTEM VENTING in appropriate
REMOVAL & INSTALLATION article.
NOTE:
Not all natural gas vehicles are equipped with Fuel Rail Pressure (FRP)
sensor. On vehicles without FRP sensor, use values supplied by fuel rail
pressure gauge.
2003 Ford Pickup F150
2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline