P0118 Fault Code in 1997 Ford Explorer AWD 5.0L: Diagnosis and Solutions
Hello, I'm new to this forum and currently dealing with a 1997 Ford Explorer AWD with a 5.0L engine that has triggered a P0118 diagnostic trouble code. The temperature gauge functions normally and reads correctly — it doesn't reach the high end and stays in the middle range. While I can clear the P0118 code using an OBD2 scanner, it returns within minutes. Additionally, the factory tachometer appears to be reading approximately double its intended value. This vehicle was recently obtained from a friend who has been unable to drive it for several years; it has sat idle for a long time and has had exposure to mice under the hood. I previously repaired a chewed ground wire that was causing the speedometer to malfunction. Given these conditions, I'm concerned about potential sensor or wiring issues. Could this P0118 code be related to the engine coolant temperature (ECT) sensor or its wiring? Is there any known issue with the 1997 Ford Explorer AWD's ECT circuit that might explain both the gauge behavior and tachometer inaccuracy?
Inspect the Engine Coolant Temperature (ECT) sensor and its associated wiring for the P0118 code. The temperature gauge uses a separate sensor circuit from the ECT, so if the gauge reads normally, it suggests that the gauge-side sensor is functioning correctly. However, the P011 or ECT sensor malfunction could still cause inaccurate engine temperature readings and affect other systems such as fuel delivery or tachometer behavior due to sensor signal interference.