The P1289 DTC relates to a specific Cylinder Head Temperature (CHT) sensor circuit performance issue. Locating this sensor quickly requires understanding its typical placement:
Preparation
- Ensure Safety: Park vehicle on level ground, engage parking brake, disconnect negative battery cable before inspection.
- Consult Resources: Have vehicle service manual or reliable wiring diagram available.
- Locate Engine: Identify the target cylinder head or specific engine bank referenced in the P1289 code context.
Typical P1289 CHT Sensor Locations (Common Engines)
- V-Type Engines (e.g., Ford Triton V8, V10): Often installed directly into the cylinder head, typically near the center of the head or close to the exhaust manifold.
- Transverse V6/V8 Engines: Commonly mounted on the rear cylinder head (bank facing firewall), potentially behind the intake manifold.
- Inline Engines: Usually positioned on the side of the cylinder head facing the front of the vehicle or near the thermostat housing/exhaust manifold. Look for wiring harness plugs routing towards the thermostat area.
Key Visual Identification
- Sensor Type: Appears as a threaded metal probe (brass or steel), typically with 1 or 2 wires.
- Harness Connector: Look for a single-pin (signal) or dual-pin (signal + ground) weatherproof connector near the identified cylinder head.
- Mounting: Screwed directly into cylinder head metal. May sometimes be near cylinder head coolant passages or temperature sending units.
Step-by-Step Finding Process
- Identify Engine Bank: Based on P1289 diagnostic details or manual, determine which cylinder head (e.g., Bank 1, Bank 2) contains the sensor causing the code.
- Trace Wiring: Visually follow the engine wiring harness running along the suspect cylinder head. Look for connectors branching off towards the head surface. The CHT sensor connector is often very similar to, but distinct from, the nearby Engine Coolant Temperature (ECT) sensor.
- Check Head Surface: Inspect the top and sides of the target cylinder head thoroughly. Use a good light source and mirror if necessary, especially for rear-mounted sensors. Feel carefully behind intake components.
- Cross-reference: If located, confirm sensor identity using the wiring diagram (wire color coding typically matches the diagram) and compare it to the known location of the ECT sensor.
Troubleshooting Tip
Sensor Position Confusion: The P1289 CHT sensor is commonly misplaced near the thermostat housing or mistaken for the cylinder block temperature sensor. Focus attention directly on the metal of the identified cylinder head.