Parts for your 2018 Toyota Crown-Temperature sensors

2018 Toyota Crown temperature sensors — what they do and how to look after them

Temperature sensors are absolutely fitted to the 2018 Toyota Crown. Toyota’s service literature for the S220 series (2018–) details multiple sensors: the Engine Coolant Temperature (ECT) sensor in the Engine/Hybrid System – Cooling section (Toyota TIS Repair Manual), the Outside Air Temperature sensor in the Air Conditioning (Automatic A/C) section, Intake Air Temperature sensing in the engine intake/MAF documentation, transmission fluid temperature sensing in the Automatic Transmission diagnostics, and (on hybrid models) HV battery temperature sensors in the Hybrid System and Battery Cooling sections (Toyota New Car Features/Repair Manual). With those references, temperature sensors are both relevant and essential on this model.

On the Crown, temperature sensors quietly keep everything behaving nicely under the bonnet. The ECT sensor tells the engine computer how warm the engine is, helping dial in cold-start fuelling, ignition timing, idle speed, radiator fan control and thermostat strategies. Intake air and ambient temp sensors tweak fuel trims and climate control, while the transmission and hybrid systems watch fluid and battery temps to protect components and maintain smooth performance and economy.

They’re not a regular “replace by kilometres” item, but they do age. If the Crown starts hard when cold, runs rich, the temp gauge is odd, the radiator fans roar from cold, the A/C behaves strangely, or a hybrid drops performance on a hot day, a dodgy temp signal could be the culprit. A quick check on a scan tool is handy: after an overnight cold soak, ECT and ambient readings should be close to each other. Any big mismatch points to the sensor or its wiring.

• Common temperature sensors on a 2018 Crown:
  • Engine Coolant Temperature (ECT) — usually at the water outlet/thermostat housing.
  • Intake Air Temperature (IAT) — often integrated with the MAF.
  • Outside Air Temperature — clipped behind the front bumper/grille.
  • Transmission Fluid Temperature — within the transmission/valve body.
  • Hybrid Battery Temperature (hybrid models) — inside the HV battery pack.

Replacement tips: let the engine cool, depressurise the cooling system, and use Toyota Super Long Life Coolant (pink) when refilling. Swap the ECT sensor with a new sealing washer/O-ring, and torque it to spec from the manual — overtightening can crack housings. Don’t use thread tape unless the manual explicitly calls for it. After refilling, bleed air properly to avoid hot spots. For hybrid battery temp sensors, leave it to a technician with HV accreditation — that job involves high-voltage safety gear. The ambient sensor is simple: if it’s snapped off or reading silly values, it usually clips out and in.

Preventative care is mostly about good connectors and clean cooling systems. Keep terminals clean and dry, fix any coolant leaks quickly, and follow proper coolant change intervals. That keeps every temp reading honest and the Crown running sweet across Australia and New Zealand’s wide-ranging climates.

Popular questions

Where is the engine coolant temperature sensor on a 2018 Toyota Crown?
On most 2018 Crown engines, the ECT sensor sits at the water outlet/thermostat housing on the cylinder head, near the upper radiator hose. Exact placement varies by engine (e.g., 8AR‑FTS turbo petrol vs A25A‑FXS hybrid), but it’s typically right where coolant exits the engine.

Can a faulty temperature sensor hurt fuel economy?
Yes. If the ECT or IAT reads colder than reality, the engine runs richer, chewing more fuel and causing rough cold starts. If it reads too hot, it can pull timing and reduce performance. A quick scan and comparison to ambient temperature is the fastest way to confirm.

Do temperature sensors need routine replacement?
There’s no fixed interval. They’re replaced on condition — failed readings, related fault codes, or damage. Check them whenever the cooling system is serviced, after front-end repairs (for the ambient sensor), or if there are drivability or A/C quirks. Hybrid battery temp sensors aren’t a routine service item and are handled with the pack by qualified technicians.