E-CODE 1400

Possible Causes

• •Coolant sensor circuit issue
• •Coolant sensor not functioning properly
• •Wiring issue between J1 or J2 connector and air fuel solenoid
• •Faulty air/fuel solenoid
• •Coolant sensor resistance changes with temperature
• •Voltage from coolant sensor goes down as engine warms up

Suggested Actions

1. 1Verify proper operation of the coolant sensor circuit by back probing between Wire 68 and Wire 0 at the controller to monitor voltage.
2. 2Use an external temperature measuring device (e.g., infrared temperature gun) to monitor engine temperature near the coolant sensor as it warms up.
3. 3Observe voltage drop as engine warms up. Voltage should be approximately 2.1 VDC when engine temperature reaches 246 ºF (119 °C).
4. 4If DMM indicates approximately 27 ohms, repair or replace wiring between the J1 or J2 connector and the air fuel solenoid.
5. 5If DMM does not indicate the proper resistance, replace air/fuel solenoid.
6. 6Verify proper operation of the coolant sensor circuit by back probing between Wire 68 and Wire 0 at the controller to monitor voltage while warming the engine and comparing voltage to engine temperature.
7. 7Measure the resistance of the coolant sensor circuit between Wire 68 and Wire 0 at the controller connector and compare to a table based on sensor temperature.
8. 8If voltage is high (3.3 VDC) at the controller with the coolant sensor connected, check wires, connections to the coolant sensor, and the sensor itself, and repair or replace as needed.
9. 9If voltage is low (below 3.3 VDC) with the coolant sensor connector disconnected, verify that Wire 68 is not shorted to ground or another wire.
10. 10If voltage is still low after checking for shorts on Wire 68, extract Wire 68 from the controller connector and measure the voltage out of the controller. If voltage is not 3.3 VDC (+/- 0.2), replace the controller.

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