You should get the code and post it, is it saying you have this many miles to go before it runs out or is it the code for the temp sensor because they are different and one will be easy, other will put a sizable hole in your wallet. You cant change just the sensor on the urea tanks, the whole tan needs to be replaced.

Get the code, scan it yourself, take it to autozone for a free scan.

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2011 35d