I had a coolant leak on my 06 XKR, which I traced to the reservoir.
While replacing the reservoir, I went ahead and flushed the coolant - not with pressure,
but just by filling and draining with fresh water repeatedly,
probably about six times until i had clear water when draining.
Afterward, I added a gallon of Dexcool (100% - not the pre-mix),
plus about a pint of the 50/50 premix that I had left over from just topping it off over time,
(before I found the leak and replaced the reservoir) in addition to the water still in the system.

Several weeks later I had the engine light come on with error code P0128.

I disconnected the battery in an attempt to clear the code, but it didn't go off.
However, a few days later it did turn off.
But as luck would have it, it came on again a few weeks later.

I understand the code 0128 is likely the thermostat,
but I've also seen reference to possible contaminated coolant.

It just seems coincidental that I get this error after replacing the coolant.

Does anyone believe it could be a coolant issue
(contaminated or maybe incorrect mixture)
vs the thermostat being faulty?

Thanks for any insight or suggestions.

Cheers!
Mike

 

The vehicle spec book indicates it should be 50% water, 50% DEXCOOL. The total capacity is 12.1 US quarts.

Maybe you can find a gauge to tell you what the mix is in your car. There used to be these cheap gravity gauges at the parts store. Maybe there is a scale for DEXCOOL.

How were you draining the coolant? From the passenger-side plug on the radiator? Or was it from the bottom of the engine block? Either way, I suspect the heater core would not be drained...

Are there other codes?

Best of luck, keep us posted.

 

I don't know of or have heard of a sensor for the cooling system concentration. The code is telling you that the system is not responding to the correct temperatures. Coolant wise a low level where the temp sensor is without water due to an air bubble could cause that sensor to kick out that reading.
Before tearing into it I would recommend manually setting the climate system on HIGH heat and take it for a short drive and then let it cool and check the coolant level.
If you find it low top it off with 50/50 and go for another drive. Keep it up until you are sure that all air is out of the system. The code should clear itself but if not clear it with OBD reader.
Give it a try and let us know how you make out.

 

Vern, I think fmertz was referring to hydrometer that measure the specific gravity of ethelyne glycol coolant mixtures. The bad news is I've read that they are unreliable for propylene glycol coolant mixtures. The later's specific gravity/concentration curve is beyond non linear - it actually inverts above 70% concentration. (See that, a fascinating opening line for the next time you meet a super model ).

Ttytt I forget which coolant we use and I'm not sure how they measure the level of protection for propelyne glycol.

John

 

Thanks for the reply, Fred

I'll stop by my local auto parts store - they say they have a cheap hydrometer scale
that works for the Dexcool - since I'm not sure about my mixture,
its a good idea to check to see if I'm within the proper range of freeze protection.

I drained it from the radiator plug.

Other code is P1111 - System Passed

Cheers!

 

Thanks for the reply, Vern.

I'll give this a try this afternoon.

Cheers!

 

Whenever I have had to replace the coolant expansion tank on either of our Jaguars, I have had to drive the car to burp the cooling system and add slightly more coolant each time during the course of the next several mornings before the coolant level finally stayed where it belonged. If you did not burp your system, I bet you simply do not have enough fluid in it regardless of your current water/coolant mixture....

 

Thanks for the reply, Jon.
Yep - that was the cause.
When I opened the reservoir to check the freeze protection level,
sure enough, the fluid was a little low.
I topped off with about 5-6oz,
and after the first drive, the light went off on its own.
(not sure why I didn't see the low engine coolant message)

Thanks for all your replies - hopefully this could help others.

Cheers!
Mike

 

Be sure to keep checking the level in your reservoir first thing every morning for at least three or four days. Not uncommon for it to take that long to burp all of the air out of the system....