Parts for your 2018 Honda Accord-Temperature sensors

2018 Honda Accord temperature sensors: what they do and how to look after them

Temperature sensors are absolutely fitted to the 2018 Honda Accord. Honda’s 2018 Accord Service Manual and parts catalogue list multiple sensors, including the engine coolant temperature (ECT) sensor, intake air temperature (IAT) sensor, ambient/outside air temperature sensor, transmission fluid temperature sensor (CVT and 10‑speed), and, on Hybrid models, battery temperature sensors. These are also reflected in factory diagnostic routines and OBD‑II trouble codes used on the Accord (for example, ECT-related DTCs such as P0115–P0119 and thermostat performance P0128), as documented across Honda service information and mainstream repair databases.

On this Accord, temperature sensors are the quiet achievers that keep everything running sweet under the bonnet. The ECT sensor tells the ECU how warm the engine is so it can sort cold starts, fuel trim, ignition timing, radiator fan operation and fast‑idle. The IAT sensor helps fine‑tune fueling as the weather swings from a frosty Kiwi morning to a scorching Aussie arvo. The ambient sensor feeds the climate control and the dash’s outside temp display, while the transmission fluid temp sensor helps the CVT or 10‑speed choose the right shift strategy to protect the gearbox. Hybrid models rely on battery temp sensors to balance performance and longevity.

They’re not a regular “replace by kilometres” item, but they do deserve a check during servicing. A technician can scan live data to confirm the ECT rises smoothly from cold and stabilises at normal operating temperature, and that IAT and ambient readings look realistic. Odd readings, hard cold starts, black fuel smell, the radiator fan running flat‑out when the engine’s cold, dopey A/C behaviour or poor shifting can all point to a dodgy temp sensor or its wiring.

• Keep the cooling system healthy with the correct Honda Type 2 coolant, a crook thermostat or low coolant can mimic a bad ECT.
• Inspect connectors for green corrosion and damaged pins, clean gently and reseat.
• If replacing an ECT sensor, only do it with the engine stone cold. Expect some coolant loss, fit the new sealing washer/O‑ring as supplied, and top up and bleed the system properly.
• IAT sensors can be part of the MAP/intake assembly, handle delicately and don’t drown them in harsh cleaners.
• Use quality parts, genuine or reputable aftermarket to maintain accuracy.

Done right, temperature sensors rarely give grief. A quick scan and a few sensible checks at each service will keep the Accord comfy, efficient and happy to rack up the kilometres.

Popular questions

Where is the engine coolant temperature (ECT) sensor on a 2018 Honda Accord?
On most 1.5T and 2.0T petrol models, the ECT sensor is threaded into the engine near the thermostat housing at the cylinder head end. It has a small two‑pin connector. Access is from the top with the engine cover off, though space can be tight.

If you’re unsure, follow the upper radiator hose back to the engine, the sensor is usually close by. Always work on a cold engine to avoid burns and coolant spray.

Do temperature sensors need routine replacement?
No. They’re monitored by the ECU and are replaced on condition. During servicing, a tech will confirm their readings make sense and check wiring/connectors. If a sensor drifts out of spec or throws a code, that’s the time to replace it.

Keeping coolant fresh, connectors clean and intake plumbing sealed helps sensors live a long life.

What fault codes point to a bad temperature sensor on this Accord?
Common ECT-related codes include P0115–P0119 and P0128 (thermostat performance). IAT issues often trigger P0111–P0113. Transmission temp sensor faults may log under the TCM with temperature sensor circuit codes.

A proper diagnosis checks live data, wiring integrity and coolant level/thermostat operation before condemning the sensor.