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Discussion Starter · #1 ·
Hi everyone

Just wanted to share a remedy to the above faults.

Fault P2681 (coolant bypass valve open circuit) appeared a couple if months ago. I replaced the valve with a good used item but the fault remained.

Next (at the same time) I got P2556 Engine coolant Level sensor/switch (level ok in the expansion vessel) P0116 Engine Coolant Temperature Sensor 1 (engine cooling fan running at full speed almost all the time and engine not getting up to normal operating temperature) the stop/start stopped happening and the cruise control stopped functioning completely (no response from any stalk operation).

I put the car into an independent "specialist" garage, expecting some sort of relay or fuse problem (couldn't find a faulty one myself).

They did a coolant pressure test and found a slight leak "possibly from the thermostat housing" and quoted £792 to replace the housing, expansion vessel (to replace the level sensor) and temperature sensor 1. (On top of the £102 diagnosis charge)

I didn't think it was possible for all of these to fail simultaneously and thought it could be the leaking coolant causing a short somewhere.

So I replaced the thermostat housing (and water pump while I had it out) and found that the electrical connector on the thermostat housing had coolant ingress and some corrosion. (Photo attached).

After refitting everything and cleaning the connector, all faults could be cleared and haven't returned.

Hope this helps someone else at some stage



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