Parts for your 1999 Nissan Navara-Temperature sensors

1999 Nissan Navara temperature-sensors: what they do and how to look after them

Temperature sensors absolutely are used on the 1999 Nissan Navara (D22). The Nissan D22 Navara Factory Service Manual (1997–2004 printings) lists an Engine Coolant Temperature (ECT) sensor in the EC and EL sections, plus a separate temperature sender for the dash gauge in the combination meter section. Petrol KA24-series engines and diesel TD27/QD32 variants both show these components, and the Nissan FAST parts catalogue for D22 backs this up with distinct part listings for the ECM’s 2‑pin ECT sensor and the single‑wire gauge sender. Many vehicles also have an Intake Air Temperature (IAT) sensor (often integrated into the MAF on petrol), and autos include a transmission fluid temperature sensor.

On a 1999 Navara, the ECT sensor feeds the ECU with actual coolant temperature so it can sort cold starts, idle speed, fuelling, and fan control. The separate dash sender keeps the gauge honest for the driver under the bonnet conditions. An IAT sensor helps trim fuelling and timing based on the air’s temp, handy for Aussie/NZ climate swings. If auto, the trans temp sensor protects the gearbox by adjusting shift strategy when things get hot.

They’re not a scheduled “replace every X km” item, but they do age. Fresh coolant (use the right Nissan‑spec long‑life coolant, mixed correctly) prevents corrosion on the ECT probe and keeps readings stable. During regular servicing, a quick scan-tool check of live data is gold: from cold start to warm idle, the ECT should climb smoothly to roughly 80–95°C and sit steady. Any wild spikes, no change, or a gauge that disagrees with scan data points to a crook sensor, wiring, or earth.

Replacement is straightforward with the right spanner: work on a cold engine, relieve pressure, drain a little coolant, unplug the connector, remove the sensor, then fit the new unit with the correct sealing washer. Don’t overtighten—use the factory torque spec from the FSM. Refill and bleed the system (heater on hot, squeeze hoses, top up as the thermostat opens), then clear any fault codes and verify temps on a scan tool. For IAT, inspect and clean the MAF (if integrated) with proper MAF cleaner, replace the IAT if readings are out of whack.

• Common symptoms: hard cold starts, high idle, poor economy, rich running or black smoke (diesel), cooling fans misbehaving, or a lazy/erratic temp gauge.
• Typical fault codes: ECT P0115–P0119, IAT P0110–P0114.
• Stick with quality parts (e.g., genuine Nissan/Hitachi) and fix any green crusty connectors while you’re there.

Where is the engine coolant temperature sensor on a 1999 Navara?

It’s typically threaded into the thermostat housing or coolant outlet neck near the front of the engine. Many D22s have two units in that area: a 2‑pin ECT sensor for the ECU and a single‑wire sender for the dash gauge. Access is under the bonnet from the top, a deep socket helps.

How do I tell if my ECT sensor is failing?

Look for hard cold starts, rough warm‑up, excessive fuel use, cooling fans that run too often or not at all, or a temp gauge that doesn’t match reality. A scan tool showing implausible or stuck temperature readings is the clincher. Check the connector and grounds before condemning the sensor.

Do I need to bleed the cooling system after changing the sensor?

Yes. After fitting the new sensor, refill, set the heater to hot, run the engine to operating temp, and squeeze the upper hose to burp air. Top up the radiator and overflow bottle as needed. Some engines have a bleed screw—use it if fitted. Recheck levels after a short drive once it’s cooled down.