Diagnostic Aids

Perform this test only when directed by QUICK TEST. EFT sensor will operate within the range of -40 to 275°F (-40 to 135°C). This system test is intended to diagnose the following components and circuits.

• EFT Sensor
• Wiring Harness Circuits (EFT & SIG RTN)
• Powertrain Control Module (PCM)

1. 1) DTC P0181: Check For KOER DTCs
   
   This DTC indicates sensor signal is greater than self-test maximum. Check for following possible causes:
   • Open Circuit In Wiring Harness
   • Faulty Wiring Harness Connector
   • Faulty EFT Sensor
   • Faulty PCM

   Start engine. Ensure engine is at normal operating temperature. Perform KOER on-demand self-test. See KOER ON-DEMAND SELF-TEST  under QUICK TEST. If DTC P0182 or P0183 is present with DTC P0181, go to next step. If only DTC P0181 is present, clear DTCs. Perform OBD-II DRIVE CYCLE. See DRIVE CYCLE PROCEDURES  under ADDITIONAL SYSTEM FUNCTIONS. Repeat QUICK TEST .

2. 2) DTC P0180, P0181, P0182 Or P0183
   
   These DTCs indicate sensor signal is greater or less than self-test maximum. Check for following possible causes:
   • Open Or Short Circuit In Wiring Harness
   • Faulty Wiring Harness Connector
   • Faulty EFT Sensor
   • Faulty PCM

   Turn ignition switch to OFF position. Disconnect EFT sensor connector. With scan tool connected, turn ignition switch to ON position.

   NOTE: If scan tool communication link error is displayed, remove jumper wire and go to step  5.

   Using scan tool, select EFTA or EFTA V PID from PID/DATA MONITOR & RECORD menu. Note EFTA V PID value. Connect a jumper wire between signal circuit (EFT A) terminal and SIG RTN terminal at EFT sensor harness connector. If EFTA or EFTA V PID value is more than 4.5 volts or -40°F (-40°C) with sensor and jumper wire disconnected, and less than .21 volt or 275°F (135°C) with jumper wire connected, replace EFT sensor. If EFTA or EFTA V PID value is not as specified with jumper wire connected and disconnected, proceed as follows:

   • For DTC P0182, go to next step.
   • For DTC P0183, go to step  5.
   • If PID value is less than 4.5 volts with EFT sensor disconnected, go to next step.
   • If PID value is more than .2 volt with jumper wire connected, go to step  5.

3. 3) Check VREF Circuit Voltage At Fuel Rail Pressure (FRP) Sensor
   
   Turn ignition switch to OFF position. Disconnect FRP sensor connector. Turn ignition switch to ON position. Measure voltage between ground and VREF terminal at FRP sensor harness connector. See Fig 2 or Fig 3 . If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to TEST C .
4. 4) Check EFT Circuit For Short To SIG RTN
   
   Turn ignition switch to OFF position. Ensure EFT sensor is disconnected. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance between PCM connector terminal for EFT circuit and PCM connector terminal No. 91. See PCM EFT TERMINAL IDENTIFICATION  table. If resistance is more than 10 k/ohms, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE . If resistance is 10 k/ohms or less, repair short between circuits.
5. 5) Check EFT Signal For Short To VREF
   
   Measure resistance between test terminal for EFT A circuit and test terminal No. 90 at breakout box. See PCM EFT TERMINAL IDENTIFICATION  table. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to VREF circuit.
6. 6) Check For Open Circuit
   
   Measure resistance of EFT A circuit between PCM connector terminal for EFT A circuit and EFT sensor harness connector. See PCM EFT TERMINAL IDENTIFICATION  table. See Fig 1. Measure resistance of SIG RTN circuit between EFT sensor harness connector and PCM connector terminal No. 91. If both resistance readings are less than 5 ohms, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE . If any resistance reading is 5 ohms or more, repair open circuit.
7. 7) Continuous Memory DTC P0180, P0181, P0182 Or P0183
   
   These DTCs indicate possible intermittent fault. Possible causes for these faults are:
   • Faulty Sensor
   • Faulty Sensor Connector
   • Faulty Wiring Harness
   • Faulty PCM

   Turn ignition switch to ON position. Using scan tool, select EFTA PID from PID/DATA MONITOR & RECORD menu. While observing PID, tap on sensor to simulate road shock. Wiggle sensor connector. If no change in temperature reading occurs, go to next step. If any change in temperature occurs, inspect connectors for loose, damaged or corroded terminals. Repair as necessary. If connectors are okay, replace EFT sensor.

8. 8) Check Sensor Wiring Harness
   
   While observing EFTA PID, wiggle and bend small sections of wiring harness working toward PCM. If fault is indicated, isolate fault and repair as necessary. If no fault is found, fault cannot be identified at this time. Testing is complete.

Fig 1: Identifying Engine Fuel Temperature (EFT) Sensor Connector Terminals

Courtesy of FORD MOTOR CO.

Fig 2: Identifying Fuel Rail Pressure (FRP) Sensor Connector Terminals (Natural Gas Vehicles)

Courtesy of FORD MOTOR CO.

Fig 3: Identifying Fuel Rail Pressure (FRP) Sensor Connector Terminals (Except Natural Gas Vehicles)

Courtesy of FORD MOTOR CO.