P0605 — PCM read only memory (ROM) error Indicates the PCM ROM has been corupted. An attempt was made to change the calibration.
Module programming error.
Damaged PCM
Reprogram or update calibration.
Reprogram VID block (use as built data).
Check for other DTC's or drive symptoms for further action.
P0703 — Brake Switch Circuit Input Malfunction Indicates PCM did not receive a brake pedal position (BPP) input. Open or short in BPP circuit
Open or short in stoplamp circuits
Damaged PCM
Malfunction in module(s) connected to BPP circuit. (Rear Electronic Module [REM] Windstar and LS6/LS8 or Lighting Control Module (LCM) Continental and Town Car.
Damaged brake switch
Misadjusted brake switch
Check for proper function of stoplamps. Follow correct Self-Test procedures, refer to Section 2 of Quick Test.
P0704 — Clutch Pedal Position Switch Malfunction When the clutch pedal is depressed the voltage goes to low. If the PCM does not see this change from high to low the DTC is set. CPP circuit short to PWR
Damaged CPP switch
CPP circuit open in the SIGRTN
Damaged PCM
When depressing the CPP switch the voltage should cycle from 5.0V down.
P0720 — Insufficient input from Output Shaft Speed sensor The output shaft speed sensor inputs a signal to the PCM, based on the speed of the output shaft of the transmission. The PCM compares this signal with the signal of the VSS or TCSS and determines correct tire size and axle gear ratio. OSS sensor circuit short to GND
OSS sensor circuit short to PWR
OSS sensor circuit open
Damaged OSS sensor
Damaged PCM
Verify sensor signal output varies with vehicle speed.
P0721 — Noise interference on Output Shaft Speed sensor signal The output shaft speed sensor signal is very sensitive to noise. This noise distorts the input to the PCM. Wiring misrouted
After market add-on
Wiring damaged
Wiring insulation wear
Check routing of harness.
Check wiring and connector for damage.
P0722 — No signal from Output Shaft Speed sensor The output shaft speed sensor failed to provide a signal to the PCM upon initial movement of vehicle. Damaged OSS connector
Damaged OSS sensor, or not installed properly
Harness intermittently shorted or open
P0723 — Output Shaft Speed sensor circuit intermittent failure The output shaft speed sensor signal to the PCM is irregular or interrupted. Harness connector not properly seated
Harness intermittently shorted, or open
Harness connector damaged
OSS sensor damaged, or not installed properly
Verify harness and connector integrity
Verify OSS sensor proper installation
P0812 — Reverse Switch (RS) input circuit malfunction The DTC indicates that the voltage is high when it should be low. Transmission shift not indicating neutral while in KOEO Self-Test
RS circuit short to PWR
Damaged reverse switch
RS circuit open or short to SIGRTN
Damaged PCM
Check RS PID while exercising shift lever in and out of reverse.
P1000 — Monitor Testing Not Complete The on board diagnostic II (OBD II) monitors are performed during the OBD II Drive Cycle. The DTC will be stored in continuous memory if any of the OBD II monitors do not complete. Vehicle is new from the factory
Battery or PCM had recently been disconnected
An OBD II monitor failure had occurred before completion of an OBD II drive cycle
PCM DTCs have recently been cleared with a scan tool
PTO circuit is shorted to VPWR or B+ or PTO is on during testing
The DTC does not need to be cleared from the PCM except to pass an inspection/maintenance test.
P1001 — KOER Not Able To Complete, KOER Aborted This Non-MIL (Malfunction Indicator Lamp) code will be set when Key On Engine Running (KOER) Self-Test does not complete in the time intended. Incorrect Self-Test Procedure.
Unexpected response from Self-Test monitors.
rpm out of specification.
Rerun Self-Test following QT1 in Section 3, Symptom Charts, STEP 1: PCM Quick Test.
P1100 — Mass Air Flow (MAF) Sensor Intermittent The MAF sensor circuit is monitored by the PCM for sudden voltage (or air flow) input change through the comprehensive component monitor (CCM). If during the last 40 warm-up cycles in key ON engine running the PCM detects a voltage (or air flow) change beyond the minimum or maximum calibrated limit, a continuous memory diagnostic trouble code (DTC) is stored. Poor continuity through the MAF sensor connectors
Poor continuity through the MAF sensor harness
Intermittent open or short inside the MAF sensor.
While accessing the MAF V PID on the scan tool, lightly tap on the MAF sensor or wiggle the MAF sensor connector and harness. If the MAF V PID suddenly changes below 0.23 volt or above 4.60 volts, an intermittent fault is indicated.
P1101 — Mass Air Flow (MAF) Sensor Out of Self-Test Range The MAF sensor circuit is monitored by the PCM for an out of range air flow (or voltage) input. If during key ON engine OFF the air flow voltage signal is greater than 0.27 volts the test fails. Likewise, if during key ON engine running, an air flow voltage signal is not within 0.46 volt to 2.44 volts, the test fails. For voltage to air flow gm/sec conversion, GO to Pinpoint Test DC and refer to Voltage To Mass Air Flow Conversion Table. Low battery charge
MAF sensor partially connected
MAF sensor contamination
PWR GND open to MAF sensor
MAF RTN circuit open to PCM
Damaged MAF sensor
Damaged PCM
A MAF V PID reading greater than 0.27 volts (KOEO) or a MAF V PID reading outside the 0.46 volt to 2.44 volts range (KOER) indicates a hard fault.
P1112 — Intake Air Temperature (IAT) Sensor Intermittent Indicates IAT sensor signal was intermittent during the comprehensive component monitor. Damaged harness
Damaged sensor
Damaged harness connector
Damaged PCM
Monitor IAT on scan tool, look for sudden changes in reading when harness is wiggled or sensor is tapped.
P1114 — Intake Air Temperature 2 Circuit Low Input Indicates the sensor signal is less than Self-Test minimum. The IAT2 sensor minimum is 0.2 volts. Grounded circuit in harness
Improper harness connection
Damaged sensor
Damaged PCM
Monitor IAT2 PID. Typical IAT2 temperature should be greater than IAT1. Refer to Section 6 : Reference Values for ranges.
P1115 — Intake Air Temperature 2 Circuit High Input Indicates the sensor signal is greater than Self-Test maximum. The IAT2 sensor maximum is 4.6 volts. Open circuit in harness
Sensor signal short to power
Improper harness connection
Damaged sensor
Damaged PCM
Monitor IAT2 PID. Typical IAT2 temperature should be greater than IAT1. Refer to Section 6 : Reference Values for ranges.
P1116 — Engine Coolant Temperature (ECT) Sensor Out of Self-Test Range Indicates the ECT sensor is out of Self-Test range. Correct range is 0.3 to 3.7 volts. Overheating condition
Malfunctioning thermostat
Damaged ECT sensor
Low engine coolant
Damaged harness connector
Damaged PCM
Engine coolant temperature must be greater than 10°C (50°F) to pass the KOEO Self-Test and greater than 82°C (180°F) to pass the KOER Self-Test.
P1117 — Engine Coolant Temperature (ECT) Sensor Intermittent Indicates ECT circuit became intermittently open or shorted while engine was running. Damaged harness
Damaged sensor
Damaged PCM
Damaged harness connector
Low engine coolant
Monitor ECT on scan tool, look for sudden changes in reading when harness is wiggled or sensor is tapped.
P1120 — Throttle Position (TP) Sensor Out of Range Low (RATCH too Low) The TP sensor circuit is monitored by the PCM for a low TP rotation angle (or voltage) input below the closed throttle position through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) remains within the calibrated self-test range but falls between 3.42 and 9.85% (0.17 and 0.49 volt), the test fails. TP circuit with frayed wires
Corrosion on TP circuit connectors
VREF open to TP sensor
VREF short to SIG RTN
TP sensor loose pins
A TP PID (TP V PID) between 3.42 and 9.85% (0.17 and 0.49 volt) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.
P1121 — Throttle Position (TP) Sensor Inconsistent with MAF Sensor The PCM monitors a vehicle operation rationality check by comparing sensed throttle position to mass air flow readings. If during key ON engine running self-test the comparison of the TP sensor and MAF sensor readings are not consistent with calibrated load values, the test fails and a diagnostic trouble code is stored in continuous memory. Air leak between MAF sensor and throttle body
TP sensor not seated properly
Damaged TP sensor
Damaged MAF sensor
Drive vehicle and exercise throttle and TP sensor in all gears. A TP PID (TP V PID) less than 4.82 % (0.24 volt) with a LOAD PID greater than 55% or a TP V PID greater than 49.05% (2.44 volts) with a LOAD PID less than 30% indicates a hard fault.
P1124 — Throttle Position (TP) Sensor Out of Self-Test Range The TP sensor circuit is monitored by the PCM for an out of range TP rotation angle (or voltage) input. If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) reading is less than 13.27% (0.66 volt) or greater than 23.52% (1.17 volts), the test fails. Binding or bent throttle linkage
TP sensor not seated properly
Throttle plate below closed throttle position
Throttle plate/screw misadjusted
Damaged TP sensor
Damaged PCM
A TP PID (TP V PID) reading not between 13.27 and 23.52% (0.66 and 1.17 volts) in key ON engine OFF or key ON engine running indicates a hard fault.
P1125 — Throttle Position (TP) Sensor Intermittent The TP sensor circuit is monitored by the PCM for sudden TP rotation angle (or voltage) input change through the comprehensive component monitor (CCM). If during the last 80 warm-up cycles in key ON engine running the PCM detects a TP rotation angle (or voltage) changes beyond the minimum or maximum calibrated limit, a continuous diagnostic trouble code (DTC) is stored. Poor continuity through the TP sensor connectors
Poor continuity through the TP harness
Intermittent open or short inside the TP sensor
While accessing the TP V PID on the scan tool, lightly tap on the TP sensor or wiggle the TP sensor connector and harness. If the TP V PID suddenly changes below 0.49 volt or above 4.65 volts, an intermittent fault is indicated.
P1127 — Exhaust Not Warm Enough, Downstream Sensor Not Tested The HEGO monitor uses an exhaust temperature model to determine when the HO2S heaters are cycled ON. The test fails when the inferred exhaust temperature is below a minimum calibrated value. Engine not operating long enough prior to performing KOER self-test.
Exhaust system too cool.
Monitor HO2S Heater PIDs to determine their ON/OFF state. DTC P1127 will be present if the exhaust is not hot.
P1128 — Upstream Oxygen Sensors Swapped from Bank to Bank (HO2S-11-21) The HEGO monitor checks and determines if the HO2S signal response for a fuel shift corresponds to the correct engine bank. The test fails when a response from the HO2S(s) being tested is not indicated. Crossed HO2S harness connectors (upstream).
Crossed HO2S wiring at the harness connectors (upstream).
Crossed HO2S wiring at the 104-pin harness connectors (upstream).
P1129 — Downstream Oxygen Sensors Swapped from Bank to Bank (HO2S-12-22) The HEGO monitor checks and determines if the HO2S signal response for a fuel shift corresponds to the correct engine bank. The test fails when a response from the HO2S(s) being tested is not indicated. Crossed HO2S harness connectors (downstream).
Crossed HO2S wiring at the harness connectors (downstream).
Crossed HO2S wiring at the 104-pin harness connectors (downstream).
P1130 — Lack of HO2S-11 Switch, Fuel Trim at Limit The HEGO Sensor is monitored for switching. The test fails when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit. Electrical:
Short to VPWR in harness or HO2S
Water in harness connector
Open/Shorted HO2S circuit
Corrosion or poor mating terminals and wiring
Damaged HO2S
Damaged PCM
Fuel System:
Excessive fuel pressure
Leaking/contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system
Induction System:
Air leaks after the MAF
Vacuum Leaks
PCV system
Improperly seated engine oil dipstick
EGR System:
Leaking gasket
Stuck EGR valve
Leaking diaphragm or EVR
Base Engine:
Oil overfill
Cam timing
Cylinder compression
Exhaust leaks before or near the HO2S(s)
A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt indicates a normal switching HO2S.
P1131 — Lack of HO2S-11 Switch, Sensor Indicates Lean A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1132 — Lack of HO2S-11 Switch, Sensor Indicates Rich A HEGO sensor indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1137 — Lack of HO2S-12 Switch, Sensor Indicates Lean The downstream HO2S sensors are forced rich and lean and monitored by the PCM. The test fails if the PCM does not detect the output of the HO2S in a calibrated amount of time. Pinched, shorted, and corroded wiring and pins
Crossed sensor wires
Exhaust leaks
Contaminated or damaged sensor
P1138 — Lack of HO2S-12 Switch, Sensor Indicates Rich See DTC P1137
P1150 — Lack of HO2S-21 Switch, Fuel Trim at Limit See DTC P1130
P1151 — Lack of HO2S-21 Switch, Sensor Indicates Lean A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1152 — Lack of HO2S-21 Switch, Sensor Indicates Rich A HEGO sensor indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1157 — Lack of HO2S-22 Switch, Sensor Indicates Lean See DTC P1137
P1158 — Lack of HO2S-22 Switch, Sensor Indicates Rich See DTC P1137
P1168 — Fuel Rail Pressure Sensor in Range But Low The comprehensive component monitor (CCM) monitors the FRP pressure for acceptable fuel pressure. The test fails when the fuel pressure falls below a calibrated value. Low fuel pressure
Damaged FRP sensor
Excessive resistance in circuit
Low or no fuel
A FRP PID value below 551 kpa (80 psi) indicates a failure
Low or no fuel
A FRP PID value greater than 896 kpa (130 psi) indicates a failure
P1169 — Fuel Rail Pressure (FRP) Sensor in Range But High The comprehensive component monitor (CCM) monitors the FRP pressure for acceptable fuel pressure. The test fails when the fuel pressure falls below or exceeds a minimum/maximum calibrated value for a calibrated period of time. High fuel pressure
Low fuel pressure
Damaged FRP sensor
Excessive resistance in circuit
P1180 — Fuel Delivery System — Low The PCM receives fuel tank pressure (FTP) information from the natural gas module (NG), which uses the information to infer fuel rail pressure (FRP). The test fails when the inferred pressure is less than a minimum calibrated value. Restriction in the fuel line
Plugged fuel filter
P1181 — Fuel Delivery System — High The PCM receives fuel tank pressure (FTP) information from the natural gas module (NG), which uses the information to infer fuel rail pressure (FRP). The test fails when the inferred pressure is higher than a maximum calibrated value. Fuel pressure regulator
P1183 — Engine Oil Temperature (EOT) Sensor Circuit Malfunction Indicates EOT circuit became intermittently open or shorted while engine was running. Damaged harness
Damaged sensor
Damaged harness connector
Damaged PCM
EOT V PID reading less than 0.2 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault short to ground. EOT V PID reading greater than 4.5 volts with key ON and engine OFF or during any engine operating mode indicates an open circuit hard fault.
P1184 — Engine Oil Temperature (EOT) Sensor Out of Self-Test Range Indicates EOT signal was out of Self-Test range. Correct range for KOER is 0.3-1.2 volts. Damaged harness
Damaged sensor
Damaged harness connector
Damaged PCM
Engine should be at operating temperature before running self-test.
P1229 — Supercharger Intercooler Pump (ICP) Pump Not Operating The ICP DTC will be set when the PCM is calling for the pump to be operating but no current is being detected. Pump motor open circuited
Pump relay coil open
Open circuit between relay and pump
Damaged PCM
Pump motor shorted
Open circuit between PCM and relay
Poor pump ground connection
Check for voltage at relay, check fuse in power feed, check ground connection of pump motor, PID reading is on/off.
P1232 — Low Speed Fuel Pump Primary Circuit Malfunction The PCM monitors the low speed fuel pump (LFP) primary circuit output from the PCM. The test fails if: When the LFP circuit is commanded on (grounded), excessive current draw is detected on the LFP circuit; or when the LFP circuit is commanded off, voltage is not detected on the LFP circuit (the PCM expects to detect VPWR voltage coming through the low speed fuel pump relay coil to the LFP circuit). Open or shorted low fuel pump (LFP) circuit
Open VPWR to low speed fuel pump relay
Damaged low speed fuel pump relay
Damaged PCM
An open circuit or short to ground can only be detected with the low speed fuel pump.
A short to power can only be detected with the low speed fuel pump commanded on.
During KOEO and KOER Self-Test, the low speed fuel pump output command will be cycled on and off.
P1233 — Fuel System Disabled or Offline LS6/LS8:
For LS6/LS8, P1233 indicates the PCM is not receiving the fuel level information on SCP from the rear electronics module (REM). Refer to the Workshop Manual Section 413-01 for diagnostics.
All Others:
The PCM monitors the fuel pump monitor (FPM) circuit from the fuel pump driver module (FPDM). With the key on, the FPDM continuously sends a duty cycle signal to the PCM through the FPM circuit. The test fails if the PCM stops receiving the duty cycle signal. Inertia fuel shutoff (IFS) switch needs to be reset
Open FPDM ground circuit
Open or shorted FPM circuit
Damaged IFS switch
Damaged FPDM
Damaged PCM
Also for Escort/Tracer and Mustang:
Open FPDM PWR circuit
Open B+ circuit to constant control relay module (CCRM) pin 11
Open ground to CCRM pin 18 (Mustang)
Damaged CCRM
Also for Continental:
Open VPWR circuit to FPDM
The PCM expects to see one of the following duty cycle signals from the FPDM on the FPM circuit: 1) 50% (500 msec on, 500 msec off), all OK. 2) 25% (250 msec on, 750 msec off), FPDM did not receive a fuel pump (FP) duty cycle command from the PCM, or the duty cycle that was received was invalid. 3) 75% (750 msec ON, 250 OFF), the FPDM has detected a fault in the circuits between the FPDM and the fuel pump.
P1234 — Fuel System Disabled or Offline See DTC P1233. P1234 is identical to P1233 except P1234 will not illuminate the MIL.
P1235 — Fuel Pump Control Out Of Range Note: For LS6/LS8, the FPDM functions are incorporated in the Rear Electronics Module (REM). Also, the REM does not use a FPM circuit. Diagnostic information will be sent through SCP.
Indicates that the FPDM has detected an invalid or missing FP circuit signal from the PCM. The FPDM will send a message to the PCM through the FPM circuit, indicating that this failure has been detected. The PCM will set the DTC when the message is received. FP circuit open or shorted
Damaged FPDM.
Damaged PCM
The FPDM sends a 25% duty cycle (250 msec ON, 750 msec OFF) through the FPM circuit to the PCM while the fault is being detected by the FPDM. If the fault is no longer detected, the PDM will return to sending an «all OK» (50% duty cycle) message to the PCM. The PCM will keep P1235 stored in Continuous Memory.
P1236 — Fuel Pump Control Out Of Range See DTC P1235. P1236 is identical to P1235 except P1236 will not illuminate the MIL.
P1237 — Fuel Pump Secondary Circuit Malfunction Note: For LS6/LS8, the FPDM functions are incorporated in the rear electronics module (REM). Also, the REM does not use a FPM circuit. Diagnostic information will be set through SCP.
Indicates that the FPDM has detected a fuel pump secondary circuit fault. The FPDM will send a message to the PCM through the FPM circuit, indicating that this failure has been detected. The PCM will set the DTC when the message is received. Open or shorted FP PWR circuit
Open FP RTN circuit to FPDM
Open or shorted circuit in the fuel pump
Locked fuel pump rotor
Damaged FPDM
For LS6/LS8, circuits associated with the Fuel Pump relay
The FPDM sends a 75% duty cycle (750 msec ON, 250 msec OFF) through the FPM circuit to the PCM while the fault is being detected by the FPDM. If the fault is no longer detected, the PCM will return to sending an «all OK» (50% duty cycle) message to the PCM. The PCM will keep P1237 stored in Continuous Memory.
The FPDM controls pump speed by supplying a «variable» ground on the RTN circuit.
P1238 — Fuel Pump Secondary Circuit Malfunction See DTC P1237. P1238 is identical to P1237 except P1238 will not illuminate the MIL.
P1244 — Generator Load Input Low The PCM monitors the GLI circuit, and will set the DTC when the input is below calibrated limit for a calibrated amount of time. GLI circuit open or short
Damaged voltage regulator/generator
Damaged PCM
Verify operation of charging system.
P1245 — Generator Load Input High The PCM monitors the GLI circuit, and will set the DTC when the input is above a calibrated limit for a calibrated amount of time. GLI circuit open or short
Damaged voltage regulator/generator
Damaged PCM
Verify operation of charging system.
P1246 — Generator Load Input (2.0L Cougar) The PCM monitors the GLI circuit, and will set the DTC when the input is not within a calibrated limit for a calibrated amount of time. GLI circuit concern.
Damaged voltage regulator/generator
Damaged PCM.
Verify operation of charging system.
Verify battery is at proper charge.
P1246 — Generator Load Input Failed (All Others) The PCM monitors generator load from the generator/regulator in the form of frequency. The frequency range is determined by the temperature of the voltage regulator where 97% represents full load, below 6% means no load. Generator circuit short to GND
Generator circuit short to PWR
Generator circuit open
Generator drive mechanism
Damaged generator/regulator assembly
Damaged PCM
Verify battery voltage is 14.5V.
Verify generator/regulator has the correct part number.
