Chapter 1 Routine maintenance and servicing

Fuel system - electronic fuel injection engines 4C•7spilt fluid. If a sealing washer is fitted, renew itif it is worn or damaged.54 Refitting is the reverse of the removalprocedure; tighten the switch securely, thentop-up the fluid reservoir (see “WeeklyChecks”) to replace any fluid lost from thesystem, and bleed out any trapped air (seeChapter 10).Oxygen sensorNote: The sensor is delicate, and will not workif it is dropped or knocked, if its power supplyis disrupted, or if any cleaning materials areused on it.55 Release the sensor’s wiring multi-plugfrom its bracket below the starter motor, andunplug it to disconnect the sensor.56 Raise and support the front of the vehicleif required to remove the sensor fromunderneath (“see Jacking and vehiclesupport”). Remove the sensor heat shieldsthen unscrew the sensor from the exhaustsystem front downpipe; collect the sealingwasher (where fitted).57 On refitting, clean the sealing washer(where fitted) and renew it if it is damaged orworn. Apply a smear of anti-seize compoundto the sensor’s threads, to prevent them fromwelding themselves to the downpipe inservice. Refit the sensor, tightening it to itsspecified torque wrench setting; a slottedsocket will be required to do this. Reconnectthe wiring, and refit the connector plug.Fuel mixture/CO% adjustmentpotentiometer14.43 Disconnecting the intake airtemperature sensor multi-plugCrankshaft position sensor40 Refer to Chapter 5B.Coolant temperature sensor41 Refer to Chapter 3.Inlet air temperature sensor42 Remove the air inlet components asdescribed in Section 4.43 Releasing its clip, unplug the sensor’selectrical connector, then unscrew the sensorfrom the inlet manifold (see illustration).44 Refitting is the reverse of the removalprocedure.Throttle position sensor45 Remove the air inlet components asdescribed in Section 4.46 Releasing its wire clip, unplug thesensor’s electrical connector. Remove theretaining screws, and withdraw the unit fromthe throttle housing (see illustration). Do notforce the sensor’s centre to rotate past itsnormal operating sweep; the unit will beseriously damaged.47 Refitting is the reverse of the removalprocedure, noting the following points (seeillustration):a) Ensure that the potentiometer is correctlyorientated, by locating its centre on the D-shaped throttle shaft (throttle closed), and14.46 Disconnect the multi-plug from thethrottle position sensor. Sensor retainingscrews (arrowed)aligning the potentiometer body so thatthe bolts pass easily into the throttlehousing.b) Tighten the screws evenly and securely(but do not overtighten them, or thepotentiometer body will be cracked).Vehicle speed sensor48 The sensor is mounted at the base of thespeedometer drive cable, and is removed withthe speedometer drive pinion. Refer to therelevant Section of Chapter 7A or B, asapplicable.Manifold absolute pressuresensor49 The sensor is located near the centre ofthe engine compartment bulkhead.50 Disconnect the wiring multi-plug, anddetach the vacuum hose from the base of thesensor.51 Undo the two retaining screws, andwithdraw the sensor from its location.52 Refitting is the reverse of the removalprocedure.Power steering pressure switch53 Releasing its clip, unplug the switch’selectrical connector, then unscrew the switchfrom the power steering high pressure pipe.Place a wad of rag underneath, to catch any58 The fuel mixture/CO% adjustmentpotentiometer is located on the enginecompartment bulkhead below the ignitionmodule.59 Disconnect the battery negative (earth)lead (refer to Chapter 5A, Section 1).60 Disconnect the potentiometer’s wiringmultiplug (see illustration).61 Unscrew the retaining screw and removethe potentiometer from the bulkhead.62 Refitting is the reverse of the removalprocedure.4C14.47 General view of the throttle position sensor and its“D” shaped throttle spindle location (arrowed)14.60 Fuel mixture/CO% adjustment potentiometerA Securing screw B Multi-plug1595Ford Fiesta Remake