Parts for your 2003 Honda Stream-Temperature sensors

2003 Honda Stream Temperature Sensors — What They Do and How to Look After Them

Yes, temperature sensors are fitted to the 2003 Honda Stream. Honda’s factory literature confirms multiple sensors across the vehicle: an engine coolant temperature (ECT) sensor in the cooling system, an intake air temperature (IAT) sensor in the intake tract, and, on auto models, a transmission fluid temperature sensor. Climate-controlled variants also use ambient and evaporator temperature sensors. References: Honda Stream Service Manual (RN1–RN4, 2002–2006), Honda Electrical Troubleshooting Manual for Stream/Civic (2001–2005 platforms), and Honda OBD‑II DTC lists (e.g., P0117/P0118 for ECT, P0113 for IAT).

On the 2003 Stream, temperature sensors keep the whole show running smoothly. The ECT sensor tells the ECU how hot the engine is so it can sort cold-start enrichment, ignition timing, idle speed, radiator fan control, and even VTEC engagement on K-series models. The dash gauge also leans on this info. The IAT sensor helps the ECU fine‑tune fuelling and timing as intake temps swing with season and traffic. Automatic transmission models use fluid temperature to manage shift quality and converter lock‑up. For comfort, climate sensors regulate demist, heater output and A/C compressor behaviour.

They’re not “service items” with a set change interval, but they do deserve a look during routine servicing, especially on older looms and connectors.

• Tell‑tale signs of a crook temp sensor: hard cold starts, rich running, sooty exhaust, poor fuel economy, erratic temp gauge, radiator fans stuck on or never coming on, weak A/C, and fault codes like P0117, P0118, P0128, P0113 or P0711.
• Quick checks: with a scan tool, ECT should read close to ambient after an overnight soak and climb steadily to roughly 85–95 °C at operating temp, IAT should track ambient once heat‑soak settles. Any wild jumps point to wiring or sensor issues.
• Maintenance tips: keep coolant fresh (Honda Type 2 is ideal), fix any leaks, clean and re-seat sensor connectors, and avoid mixing sensor types or cheap no‑name parts that can skew readings.
• Replacement pointers: always start with a stone‑cold engine. For the ECT (mounted on the thermostat housing/outlet at the front of the engine), relieve pressure, catch any coolant, swap the sensor with a new sealing washer or O‑ring, then refill and bleed the cooling system. The IAT usually pops out of the airbox or intake tube, refit with the correct clip or O‑ring. Transmission temp sensors are generally only replaced when fault‑coded.

As the Honda Stream shares core systems with the same‑era Civic/CR‑V, the above behaviour and troubleshooting steps match what Honda’s manuals specify for RN1–RN4 platforms.

Popular questions

Where is the engine coolant temperature sensor on a 2003 Honda Stream?
The ECT sensor is fitted on the thermostat housing/outlet at the front of the engine. On RN1/RN2 (1.7‑litre) and RN3/RN4 (2.0‑litre) variants, it’s accessible from the top/front of the bay. Look for a two‑pin connector on the alloy housing where the upper radiator hose meets the engine.

Do temperature sensors need calibration after replacement?
No special calibration is required. The ECU learns on the fly. As long as the correct spec sensor is installed, the connector is clean, and the cooling system is properly bled with the right coolant, readings will be accurate without any coding.

Can a bad temp sensor make the radiator fans run all the time?
Yes. If the ECU sees an implausible high reading or an open circuit, it may run the fans as a failsafe and log a code (like P0118). That said, a stuck relay, A/C request, or wiring fault can cause the same symptom, so confirm with a scan tool before replacing parts.