expedio2005
Full Access Member
I've had my 2014 lr4 hse lux in the shop for a P0128-00 - Coolant thermostat (coolant temperature below thermostat regulating temperature) (AB) code. The check engine light is on and my GAP reader shows the coolant gets to 163 degrees and stays there. I took it to the shop and they replaced the thermostat. On the way home with the new thermostat, the check engine light came back on with the same code. Now it's back in the shop and the mechanic states he's tried 3 different thermostats which didn't fix the issue. I got a text from them on friday last week stating they found the problem and it's the heater bypass valve in the crossover pipe behind the engine. The rear manifold/crossover pipe was changed out 1 year ago and I wasn't aware there is a coolant bypass valve in it, just a coolant sensor. Any thoughts on this? I'm concerned they are working on the wrong thing. I've googled heater bypass valve and I'm unable to find anything for my vehicle.
