Parts for your 2001 Toyota Crown-Temperature sensors

2001 Toyota Crown temperature sensors — what they do and how to look after them

According to Toyota technical literature for the S170-series Crown (including the Toyota Crown Repair Manual, the Electrical Wiring Diagram, and New Car Features documents), the 2001 Crown absolutely uses multiple temperature sensors. These include the engine coolant temperature (ECT) sensor for the ECU, an intake air temperature (IAT) element within the airflow meter, ambient and evaporator temperature sensors for the automatic climate control, and an automatic transmission fluid temperature sensor. On some engines there’s also a separate sender for the dash gauge. So temperature sensors are very much relevant on this model.

On a 2001 Toyota Crown, temperature sensors keep the engine, transmission, and climate control behaving as they should. The ECT sensor tells the ECU how warm the engine is so it can set cold-start fuelling, ignition timing, idle speed, thermo-fan operation and even transmission shift strategy. The IAT helps fine-tune fuelling as air density changes. The climate system relies on ambient and evaporator thermistors to deliver steady cabin temps without fogging. When any of these drift out of spec, the driver can see hard cold starts, rough idle, thirsty fuel use, lazy performance, erratic temp gauge readings, fans running at odd times, or average air-con performance.

While temperature sensors aren’t “consumables”, they do age. During routine servicing, it pays to:

• Scan live data and compare cold readings to ambient, then check hot readings after a proper drive.
• Inspect connectors for green corrosion, broken locks, oil or coolant wicking into looms.
• Keep the cooling system healthy: fresh Toyota-approved coolant, correct mix, and no air pockets.
• Make sure engine grounds are clean and tight, poor earths skew sensor signals.

Replacing an ECT sensor on the Crown is straightforward for a competent DIYer or a workshop. Always start with a stone-cold engine. Relieve any cooling system pressure, disconnect the plug, drain a little coolant if needed, then swap the sensor (and sealing washer if required). Tighten only to the factory spec from the Toyota manual—over-tightening can crack housings. Refill with the correct coolant, bleed air properly, confirm leak-free, then verify temperatures and fan operation with a scan tool. Sticking with genuine Toyota or quality DENSO parts helps avoid rework.

Common red flags worth checking out:

• Temp gauge erratic or fans running constantly
• Cold-start richness, sooty tailpipe, or higher-than-usual fuel use
• Air-con not getting cold at idle but fine on the move

Sorted sensors make a noticeable difference on these cars—nicer manners, better economy, and longer engine life, which is exactly what Crown owners are chasing.

Where is the engine coolant temperature sensor on a 2001 Toyota Crown?

On S170 Crown engines (such as 1G-FE and JZ-series variants), the ECT sensor is typically threaded into the coolant outlet/thermostat housing at the front of the cylinder head, near the upper radiator hose. It’s accessible from the top in most trims. Some engines also have a separate single-wire sender for the dash gauge nearby—don’t mix them up.

How can they tell if a dodgy temp reading is the sensor or the thermostat?

Use a scan tool first: if the ECU’s ECT value never reaches normal even after a decent drive, but the radiator hose warms up early and the cabin heat is weak, the thermostat may be stuck open. If the ECU sees crazy spikes or values that don’t match the actual engine condition (stone cold start reading 60°C, for example), suspect the sensor or its wiring. Overheating with the top hose rock-hard and fans roaring often points to a stuck-closed thermostat, not the sensor.

Does the 2001 Crown have more than one temperature sensor?

Yes. Besides the ECT sensor for the ECU, the Crown uses an intake air temperature element (within the airflow meter), an ambient and an evaporator sensor for the A/C, and an automatic transmission fluid temperature sensor. Some engines also include a separate sender for the dash gauge. Each plays a different role, so diagnosis should consider all of them.