2000 Toyota TROOPER 3.5L Engine Code PO128 - Sensor or Thermostat Issue?
I've reviewed the reference tables for my 2000 Toyota TROOPER with a 3.5L engine, but I can't locate any information about fault code PO128. The AutoZone technician suggested that the issue might be related to the engine operating below optimal temperature. I replaced the coolant temperature sensor, but the problem persists. Could this code be caused by a faulty thermostat instead? Any insights or troubleshooting steps for this specific model?
You may have changed the wrong part—double-check that you replaced the coolant temperature sensor, not the thermostat. A malfunctioning thermostat can cause the engine to run too cold, which often triggers code PO128 in vehicles like the 2000 Toyota TROOPER.