Before I begin I will say that I did research previous threads however I feel my situation may be a little different.

About 2 months ago I got the CEL and took it to Autozone, got code p2098, bank 2 02 sensor I believe. During this time I figured I would use up the tank then get new gas and check later on. Anyways the CEL went away randomly for a day or two, then came back. A few days later I had battery problems (it was pretty cold for a few days) so had to get a jumpstart.

Anyways I checked today to make sure the p2098 was the reason of the CEL but now it appears to be a p0400, the which is a problem with the EGR from what I've seen. So I realize these are slightly correlated, would fixing the EGR resolve the problem or is the underlying issue still the 02 sensor?

I should clarify I had an exhaust shop check from cracks and a leak, which they confirmed there was not - contradicting what the dealership told me (they wanted to replace both cats and 02 sensors (the car only had 2 o2 sensors according to them for $5k)

Any help is greatly appreciated!!!

 

My valve stuck closed at around 65,000 miles, giving me the P0400. The part was $109 and labor of an hour cost $90 at a local garage, been fine for 45,000 miles.

O2 sensors are a common failure item, you WILL be replacing one or more some day, but a P0400 is in the EGR itself. At the top of this forum there is a list of all codes, you can look them up yourself (and with an Ultragauge or similar app, you can READ them yourself, too.)

I see you have learned that taking a Mercedes to a Chrysler dealer is a bad idea. That is a lesson you should not forget.

 

Come to think about it, I got the P401 code - too little flow.
You may want to yank the electrical connector off the EGR and confirm the pins are not corroded, wet or gritty. Work the connector on and of 2 or 3 times to clean it and see if the light goes out in a few days.

Keep in mind an EGR stuck closed will give you quicker throttle response but make you unable to pass an emissions test. A valve stuck OPEN will slow your throttle response, and keep you from passing a test.

 

One more thing, it sounds to me like you need a new battery. And remember, the battery is your primary source of filtering of the electrical power in the car. These cars will do all sorts of strange things with a weak battery.

Replace the battery before you end up being towed and charged diagnostic fees over nothing more than a weak battery. Yes, it has happened to some here.

And, it happened to me with my Durango. (Boss would not change the old battery until it COST him to...)

 

Just some thoughts:
1) A dealer who has a service department that know what it is doing is a jewel to be treasured.
2) Most shops figure a customer will be back at least once on every job and price accordingly.
3) Someone needs to pay for the dealer's family's education and needful yacht.
4) In many locations it is fairly easy to become a business and qualify for wholesale prices. Just be careful to render unto Caesar.

It has never been so easy/cheap to analyze a car's problems. Every Crossie has at least a vestigial OBD-II and by now nearly everyone has a smart phone (well except those who like edible fruit). $17 investment is all you need. Everything else is online.

And a final thought: anyone who really understands automotive computers and electrical system probably has an air conditioned job doing something else possibly involving aircraft.

 

or is retired like onehundred80 and enjoys helping us peons out.

 

Thanks for the advice all- the battery was "new" (he said the tires were and they were new - no reason to not believe him) according to the previous owner back when I bought it in the end of July. However following this cold blast, the battery level was all the way down to 0, they recharged it for free at auto zone and it has worked ever since, however it is also warmer since as well. The AAA guy said my alternator was ok however the auto zone guy told me to check the alternator.

One thing I have learned is that I really need to learn how to do a lot of this work on my own. Dealing with many others who will probably learn as they go (the dealership didn't have a XF mech) will just prove to be pretty costly. This forum has proved very helpful but without a proper workspace it becomes pretty difficult, however I am pretty resourceful.

So while I wouldn't mind changing the battery, it would seem odd to change a battery that is only 6 months old.

 

While it is possible your alternator isnt charging right or that your have something draining the battery while it is parked, I'd guess the battery is most likely the issue.

There is no need to charge the battery, the alternator does that. My car usually sits for 12-14 days at a tine and mine starts right up - on a four year old battery in temps of 35f.

You have something wrong.... my guess is its the battery but who really knows.

 

If I have battery troubles again I will definitely replace it. If anything then just for the peace of mind of knowing I would have the 2-3 year warranty.

I will attempt to check out the EGR and look at connectors and report back.

 

[QUOTE=Padgett;82227

by now nearly everyone has a smart phone (well except those who like edible fruit). $17 investment is all you need. Everything else is online.

[/QUOTE]

What are you implying here. I don't have a smart phone, and don't
plan on getting one unless it becomes the only option. But, I'm not offended!!!

 

OK an Android tab will work as well but are harder to carry on your belt. I have a mount in each car and just drop my phone in whichever one I drive. It then finds the amp and speakers. Sound is a lot better than that satellite thingie.