2003 Is200 Using Water Fault Code P0115

[Mbart04]

Hi, I have a lexus is200 52 plate. Aslong as the overflow tank is full it run fine and stays at temp, but when Check the overflow tank after going anywhere it's almost empty( take just under a litre). I have plugged it in and it come up with fault code p0115"engine coolant temp malfunction" while plugged in I noticed that them temp sat at 70-80c but when ignition is off it drop to -50 any ideas where to start. Engine temp sensor, thermostat? Many thanks Matt.

[Malc]

Maybe, just maybe ...... on my Mk1 Ls400 many years ago it was the expansion tank pressure cap rubber seal that had started to perish................... a new cap was the instant solution, inexpensive fix, just £6 then I think.

Malc

[Mbart04]

Thank you, is that the on the tank or one on the radiator?

[Malc]

I don't know the Is200, ............... my Ls400 was just the small separate expansion tank ......... cap, there wasn't one on the radiator, well not that I ever found anyway !

Might not be your solution but it's worth having a look.

Malc

[Mbart04]

Yeah there is a cap on the overflow tank with a overflow pipe and a pressure cap on the radiator. Where your systems the same? Yeah I'll give it try see what happens never know

[ambermarine]

The Lexus Ls400 as a closed system inclusive of the expansion tank.I am not well informed about the is200 but from what you are describing it sounds like you are losing coolant somewhere.

[steve2006]

This post appears to be in the wrong section so I'll move it to the IS forum.

As other members have kindly pointed out you need to locate where the coolant is escaping from start with the expansion bottle itself as these have been known to crack and the pressure cap.

Obviously check the radiator for leaks and all the hoses.

Any funny smells inside the car? The heater matrix is another possibility along with a seeping water pump or the pipework near to it.

With you losing a litre at a time it shouldn't be too difficult to spot where from.

The fault code you are getting could be due to the low coolant level affecting the temperature sender unit so I wouldn't be concerned by that at the moment, main thing is to locate the leak and fix it before you end up overheating the engine.