John Deere Error Code F13042 — What It Means and How to Fix It

Applies to: 6R Series, 7R Series, 8R Series, 9R Series

WARNING — Service soon

You can keep working for now. Replace the sensor before your next full day — running blind on coolant temp risks an overheating event you won't see coming.

JD F13042John DeereManually verified

Engine Coolant Temperature Sensor — Signal Out of Range

The ECU is receiving a coolant temperature reading outside the expected range. Most likely a failed sensor.

Repair difficulty

DIY — Basic tools

Repair time

30 min

Dealer cost

$350-500

What to check first

  1. 1

    Check the coolant level in the overflow tank — if it's low, top up and look for the leak first.

  2. 2

    Locate the sensor on the thermostat housing and inspect the 2-pin connector for corrosion or a pulled-out pin.

  3. 3

    Wiggle the wiring harness while the engine is running — if the code clears intermittently, it's a connector or wire issue, not the sensor.

Likely causes

  1. 1

    Faulty coolant temperature sensorMost likely

    Most common cause. Sensors typically fail after 4,000–5,000 hours. Resistance drifts outside spec and triggers the fault.

  2. 2

    Damaged wiring harness to sensorPossible

    Check for rodent damage, chafing against engine components, or corroded connectors. Wiggle the harness with the key on and watch for intermittent faults.

  3. 3

    ECU faultLess common

    Rare. Rule out sensor and wiring first. If a new sensor doesn't clear the code, have the ECU checked.

Parts needed

Tools needed

  • 10mm socket
  • ratchet
  • coolant (if drained)

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