P1486 is most often associated with cooling system problems on Honda Accords. A faulty ECT (engine coolant temperature sensor) or a stuck open thermostat is usually to blame.
If the thermostat is stuck open, the first thing you should do is remove it. In that case, replace the part and refill the cooling system as well as clear the code. Bad thermostats are the most common cause of this P1486 Honda Accord trouble code.
TSB (01-022) from Honda requires replacing the PCM if the thermostat and ECT are fine. In that case, you’re on the right track and should be able to resolve this code by replacing the PCM if you know the thermostat and ECT are working fine.
Honda P1486 Code Definition: Cooling System Malfunction
An Engine Coolant Thermistor (ECT) is a two-wire thermistor. The thermistor resistance and signal voltage decrease as the engine coolant temperature increases.
To control injector pulse width, ignition timing, and idle, the Engine Control Module (ECM) monitors ECT voltage. ECT voltage is used for shift timing and quality by the Transmission Control Module (TCM).
When the thermostat monitor fails to reach the necessary engine operating temperature after starting the engine, a Diagnostic Trouble Code (DTC) is generated.
What Are The Possible Causes Of The Code P1486 Honda?
The P1486 error can be caused by low coolant, a problem with the radiator fan circuit, or an issue with the thermostat. There is also a possibility that it is the thermostat. Other possible causes include:
- There is a poor electrical connection in the engine coolant temperature sensor circuit
- There is an open or shorted sensor harness for the engine coolant temperature
- A faulty temperature sensor for the engine coolant
- Thermostat leaks or sticks open
- Warm-up time is insufficient
- There is not enough coolant in the engine
Honda Tech Notes for Code P1486
It is usually possible to fix the problem by replacing the thermostat if there is no leak in the cooling system and the fluid level is OK.
A PGM Tester reporting a DTC set for P0128 (Cooling System Malfunction) or P1486 (Cooling System Malfunction) is the same as reporting a DTC set for P0128 or P1486 when troubleshooting a 2000-2001 Accord or 2001-2002 Civic.
Diagnostic Trouble Codes (DTCs) P0128 and P1486 are SAE or generic diagnostic trouble codes (DTCs). In some cases, the PGM Tester reports a P0128 while detecting a P1486 or vice versa, due to the similarity between these DTCs.
How Do I Find The Thermostat?
The P1486 code indicates a problem with the thermostat’s range or performance. The thermostat can be found by following the upper hose from the radiator to the engine.
You should see a flattened hose by looking at the hoses. Additionally, look for hoses that appear to have been soaked in oil, which can cause the hose to swell and restrict flow.
Is It Safe To Drive With The P1486 Honda Accord Code?
It won’t harm you if you leave it alone. PCMs have backup strategies to handle the check engine light being on. In order to pass your yearly inspection, it will need to be addressed at some point.
P1486 is typically a thermostat error code. My experience includes low coolant codes, bad temperature sensors, stuck thermostats, wiring between the PCM and ECT sensors, and PCM programming. There are cases where the PCM/ECM is faulty, even in rare cases.
There are four cylinders in the engine. The first thing to do is to connect the coolant level sensor and the coolant temperature sensor. The thermostat should be replaced if that does not work. Take it to a mechanic if none of that works.