This code indicates that the engine coolant temperature is not reaching the proper threshold for the engine control module (ECM) to switch to closed-loop operation. Closed-loop operation is when the oxygen sensor feedback is used to precisely adjust the air/fuel mixture for optimal performance and emissions. When the engine is cold, it runs in open-loop, relying on pre-programmed settings.
The problem could be caused by several things, including:
* Faulty thermostat: The most common cause. A stuck-closed thermostat prevents coolant from circulating properly, keeping the engine too cold.
* Low coolant level: Insufficient coolant reduces the engine's ability to maintain temperature. Check for leaks and top off if needed (with the correct type of coolant).
* Coolant leak: A leak will result in low coolant and prevent proper temperature regulation.
* Faulty coolant temperature sensor (CTS): The sensor might be providing inaccurate readings to the ECM.
* Water pump: A failing water pump can't circulate coolant effectively.
* Wiring or connector problems: Issues with the wiring to the CTS or thermostat can prevent correct operation.
Recommendation: Don't ignore this code. Continued driving with this problem could lead to increased fuel consumption, poor engine performance, and potential engine damage. Start by checking the coolant level and inspecting for leaks. Then, a mechanic can diagnose the root cause more accurately. Replacing a faulty thermostat is a relatively inexpensive and common fix for this code.
