The engine coolant temperature sensor is typically located on or near the engine block by the thermostat housing; the intake air temperature sensor sits in the intake duct before the throttle body; and the ambient outside air temperature sensor is usually mounted behind the front bumper on the passenger side near the radiator.
This article explains the common locations for these sensors on a 2004 Honda Accord, covering both the four-cylinder and V6 engine options. While the general placements are similar, exact positions can vary by engine type, trim, and market, so refer to the service manual or a VIN-specific diagram for absolute certainty.
Engine coolant temperature sensor (CTS)
The CTS monitors engine coolant temperature and provides data to the engine computer to regulate fuel trim and ignition timing. In most 2004 Accords, you’ll find it screwed into the coolant passage on the engine block near the thermostat housing, with a two-wire connector leading to the wiring harness.
Common placements by engine option include:
- 2.4L four-cylinder (K-series): CTS usually threads into the cylinder head area near the thermostat housing, accessible from the top or side of the engine.
- 3.0L V6 (J-series used in some 2004 Accords): CTS located on the cylinder head near the thermostat housing, with a two-wire connector.
Note that some models may position the sensor slightly differently along the coolant jacket, but it will typically be near the thermostat housing on the engine block. For precise location, consult the factory manual or a parts diagram for your exact VIN.
Intake air temperature sensor (IAT)
The IAT sensor measures the temperature of incoming air to help the ECU adjust fuel delivery. On most 2004 Accords, it’s located in the intake air path before the throttle body, either as a separate sensor in the intake hose or occasionally integrated into the MAF sensor assembly.
Typical placements by engine option include:
- 2.4L four-cylinder: A separate 2-wire IAT sensor mounted in the air intake duct just upstream of the throttle body (often near the MAF housing).
- 3.0L V6: IAT is usually in the intake plenum or in the air intake pipe just before the throttle body, as a standalone sensor or integrated with the MAF assembly.
Some models rely on the MAF sensor assembly to provide temperature data, in which case there may be no separate IAT sensor. If you have a dedicated IAT, you’ll find a small two-wire sensor in the intake path ahead of the throttle body.
Ambient outside air temperature sensor (OAT)
The outside air temperature sensor feeds the climate control and gauge cluster with current ambient temperature. In most 2004 Accords sold in North America, the sensor is mounted behind the front bumper on the passenger (right) side near the radiator core support.
Common mounting locations include:
- Behind the front bumper, on the passenger side near the radiator or grille area (clips or a small bracket).
- Occasionally positioned in the bumper cover or on the radiator support, with a small two- or three-wire harness.
If you can’t see it from underneath the bumper, feel along the lower edge of the bumper or behind the grille area to locate a small sensor with a short wiring harness.
Tips for locating sensors quickly
To speed up the search, start with the most accessible locations and follow the wiring harnesses toward the sensor bodies. Use the vehicle’s service manual or a parts diagram for VIN-specific placement if you’re unsure.
- Trace the wiring harnesses from the engine bay toward the thermostat housing to find the CTS.
- Check the intake duct just before the throttle body for a small two-wire IAT sensor or the MAF housing for integrated temperature sensing.
- Inspect the front bumper area on the passenger side behind the grille near the radiator for the OAT sensor.
Documenting the exact location on your particular engine variant will help with diagnostics, replacement, or sensor testing.
Summary
For a 2004 Honda Accord, expect three key temperature sensors: the engine coolant temperature sensor on or near the engine block by the thermostat housing; the intake air temperature sensor in the intake duct before the throttle body (or integrated with the MAF, depending on variant); and the ambient outside air temperature sensor mounted behind the front bumper on the passenger side. While these placements cover most US-spec Accords of that year, exact positions can vary by engine type and trim, so consult a VIN-specific service diagram if you need precise guidance.