Parts for your 1998 Ford Falcon-Temperature sensors

1998 Ford Falcon temperature sensors

Technical sources confirm that the 1998 Ford Falcon (AU Series I) is fitted with multiple temperature sensors central to engine and driveline management. The Ford AU Falcon Workshop Manual (WSM, Engine/PCM and Cooling System sections, 1998), Ford EEC‑V engine management literature used on AU models, and local repair guides such as Gregory’s Ford Falcon AU Series Service and Repair Manual (1998–2002) all document the Engine Coolant Temperature (ECT) sensor, intake air temperature sensing, and related circuitry. These sources outline how the PCM uses ECT and other temperature inputs for fuelling, ignition timing, idle control, radiator fan operation, and, on autos, transmission protection strategies.

On the 1998 Falcon, temperature sensors do more than run the dash gauge. The ECT sensor feeds the PCM a live reading of coolant temp so it can enrich cold starts, trim ignition timing under load, switch the thermo fans, and protect the engine if temperatures climb. There’s also intake air temperature measurement for mixture accuracy, and the auto transmission package monitors fluid temp to manage shift feel and safeguard the unit. Keeping these sensors healthy helps the AU run sweet, use less fuel, and keep its cool under the bonnet.

There’s no scheduled replacement interval for the ECT or related sensors, they’re replaced on condition. Typical red flags include hard cold starts, hunting idle, high fuel use, fans running constantly, a dead temp gauge, or OBD fault codes (e.g., P0115–P0119 ranges for ECT circuit). Good practice during routine servicing is to eyeball the connectors for green crust or broken locks, check for coolant weep around the sensor boss, and verify live data with a scan tool—coolant temp should track ambient when stone cold and climb steadily to normal operating range.

• If replacement is needed, use an OEM‑quality sensor matched to the AU’s EEC‑V calibration.
• Work on a cold engine, catch and top up coolant, and bleed air from the system afterward.
• Avoid thread sealants unless the workshop manual specifies, many AU sensors use an O‑ring seal.
• Torque to the workshop spec to prevent leaks or cracking the housing.
• Clear codes and recheck live data and fan operation after fitting.

These small parts punch above their weight. A tidy connector, correct coolant, and a quick scan at service time can save a head‑gasket drama and keep the big six or Windsor V8 happily ticking along.

Popular questions about 1998 Ford Falcon temperature sensors

Where is the engine coolant temperature (ECT) sensor on a 1998 AU Falcon?
The ECT sensor is typically threaded into the thermostat housing or coolant outlet near the front of the engine. On the AU inline‑six it’s right by the upper radiator hose area, access is straightforward from the top once the intake ducting is out of the way. Always identify the ECT (to the PCM) versus any separate single‑wire sender that feeds the dash gauge on some variants.

Do AU Falcons have a separate temp sender for the dash gauge?
Many AU variants use the PCM’s ECT signal to drive the gauge, while others use a discrete sender. Workshop‑manual identification is the safest bet: the ECT is a two‑wire thermistor feeding the PCM, whereas a gauge sender (if fitted) is often single wire to the cluster. Wiring colour and connector style make the difference clear when checked against the manual.

What symptoms point to a bad ECT sensor on an AU Falcon?
Common giveaways are rough cold running, excessive fuel use, the cooling fans stuck on or never engaging, a stubbornly low or erratic gauge, and fault codes in the P0115–P0119 range. Live data that shows an implausible reading—like sub‑zero or 130°C on a cold start—also screams ECT trouble. Ruling out wiring corrosion at the plug is part of a proper diagnosis.