OBDII Code List

P1289 MERCURY - Cylinder Head Temperature Sensor Signal Greater Than Self-Test Range

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3  What does this mean?

P1289 MERCURY Possible Causes

  • Wrong thermostat
  • Engine overheated
  • Low engine coolant level
  • Faulty Cylinder Head Temperature (CHT) sensor
  • Cylinder Head Temperature (CHT) sensor harness is open or shorted
  • Cylinder Head Temperature (CHT) sensor circuit poor electrical connection

How do I fix code P1289 MERCURY

    Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

Cost of diagnosing the P1289 MERCURY code

    Labor: 1.0

    The cost of diagnosing the P1289 MERCURY code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.

When is the P1289 MERCURY code detected?

The Engine Control Module (ECM) detected the cylinder head temp above or below expected values

P1289 MERCURY Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

P1289 MERCURY Meaning

The Cylinder Head Temperature (CHT) Sensor is mounted into the wall of the cylinder head and is not connected to any coolant passages. The CHT sends a signal to the Powertrain Control Module (PCM) indicating the cylinder head temperature. If the temperature exceeds 126°C (-258°F), the PCM disables four fuel injectors at a time. The PCM will alternate which four injectors are disabled every 32 engine cycles. The four cylinders that are not being fuel injected act as air pumps to aid in cooling the engine. If the temperature exceeds 154 °C (310°F), the PCM disables all of the fuel injectors until the engine temperature drops below 154°C (310°F).
OBDII Code P1289 MERCURY - Cylinder Head Temperature Sensor Signal Greater Than Self-Test Range - Engine-Codes.com

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