Dealership Diagnostics

[ArlingtonBeech]

So Monday I dropped my '99 750IL at the Dealership. Originally I was going to pay a reasonable price for a coolant flush. Then i figured while its there have them run some diagnostics, just for grins. When I dropped it off it had check engine light (codes P1459 and P0500) Also, the always dreaded Trifecta of brake lights.

They were kind enough to return a Laundry list of things they think need to be replaced:

They said the Transmission was delivering a bunch of faults, possibly needing to be replaced.

Claimed the Thermostat needed replacement

Claimed the EML and both Throttle Bodies needed replacement

They think both exhaust may or may not need to be replaced, possibly due to the P1459 code.


So i'm trying to decide if I still want them to flush the coolant. Or pay them to replace and repair the Electrically heated Catalyst cables.

The rest I will consider if the need arises.

Do ya'll think after 108,000 miles on my 750IL would the above listed items need to be replaced or some other means to keep them operational?

[Chief Jimbo]

I really think you should take it for a second opinion. Find someone on the board that has the software on their laptop that can read the car out for you and erase the codes and get a couple drive cycles down then reread them. Then start from there.

[ArlingtonBeech]

That's what i was thinking. I spoke to the service adviser and to see if the tech can tell my "why" he thinks that stuff needs to be replaced. I'll have them do a couple of things, but not all they said

Know of anybody with software near Austin, TX?

[Mayorchuck]

I wonder if those are old codes that had not been cleared. The P0500 is a generic code for a speed sensor. I agree you need to get a second opinion. The other code may be the ekat module under the passenger seat. Might go to the regional forum for your area and get a recommendation for a good independent mechanic for our cars.

[Sobek]

The real issue I find with BMW dealerships (and I suppose a lot of dealerships in general) is that they live and die by what the computer says. If there is a code for anything in particular - they assume it to be faulty and recommend repair / replacement. I do somewhat understand the mentality, throughput is king and if your dealer tells you something is wrong with your car and needs fixing, 99% of the time your average Joe says bugger, alright get that fixed! It's quick easy money for the dealership and your trust in them makes you nonethewiser. I seriously doubt those problems they're suggesting exist, and to be fair some of those codes can be indicative of other failures that generate secondary or false codes. Even just a disconnected and reconnected battery can result in all sorts of crazy codes from your transmission to your fuel supply - I see this all the time. 'Noise on the line' I would call it. Years back when I was talking to a BMW technician who was happy to do a free diagnostic on my car (I would personally never go to BMW for anything but I was humoring an offer), before I even took it in he wouldn't stop going on about how there would be "All sorts of codes, all sorts of problems!" with my car. "Those troublesome old 7 series!". I had to explain to him over and over that no, my car is generating no codes and no, nothing is wrong with it It was just the mentality that struck me as funny.

Absolutely get a second opinion if you are concerned. Have the codes cleared, then drive it for a week or two and have someone (independent as suggested) look at it who is more willing to diagnose and not just repair. I think you will find any potential issues will be far less than BMW is suggesting. Thermostat? Throttle bodies? Exhaust / e-cats? At 100k miles?? Almost certainly not!

[cyclops2]

Here is a highly regarded BMW indy in Austin. I took my car to him back in 2004-2006.

http://www.terrysaytherauto.com/

[chrisn7]

It quite likely that the thermostat is defective although you unlikely to notice anything in 'normal' driving. Its not the stat itself, but the map cooling connection (not the temp sensor). There are 2 wires from the stat through to the connector, and coolant gets past these either corroding the wires or preventing a signal, which then throws a code.

[Timm]

Diagnostics are so cheap and easily available these days - just do the diagnostics yourself:

http://www.meeknet.co.uk/E38/Diagnostics.htm

[Mayorchuck]

Getting fancy there Tim. Good work. That's a new one to me. I might link that up in the DIY section later.

[oldroller]

Timm, that's the best description of air/fuel modification I have ever seen in my nearly 50 years of dealing with electronic fuel systems.
It should be a 'first read' for any DIY'er. Prior to electronics, we had the 'ear' method...load it, adjust it to smooth, drive the piss out of it
to ensure no flat spots/bogging....hence the poor mpg's back then. Fun though.

Excellent presentation, tip o' the hat to yer!

[Timm]

Thanks men - it's the first of a series of articles about using diagnostics, and there will be a video to go with them.

The method we used here for setting the carburettor needle height (on two-stroke Villiers motorbikes) was to go absolutely flat out and jam the rear brake on to stall the engine - and then pop the spark plug out to see what colour it was! We moved on to the glass Colortune spark plug to see the combustion colour in real-time but just got continuously electrocuted......

Edit, just searched and they still make them:

https://www.ebay.co.uk/i/13075800424...8853793&crdt=0

[racer2086]

Wow Timm that is fantastic! Bookmarked that page to read it thoroughly.

[ArlingtonBeech]

Thanks guys. Ill be following your advise. I thought the estimates and what they were saying was a bit much, so I figured I would ask on here. i figured they say fault codes and just assumed it all needed replacement. Not a couple of weeks ago I replaced the Aux battery because it was pretty bad according to Advance Auto. It was not holding a charge a few bad cells or something along those lines.

I'm hoping to get it back tomorrow or Monday. I had the Stealership just flush the coolant.I ran into a small issue (broken o ring on bleeder screw) with loss of coolant and made an emergency addition. So I wanted it flushed. I will replace the E-kat wires that need it when I get it back. I know one was corroded and broken.

When I get a chance i'll swing it by a reputable shop. May give Terry Sayther Auto here in Austin a shot. I'll have the codes cleared and drive it for a short while and see what comes back.

I agree, Timm that's a in depth diagnosis. That will come in handy when I get her back.

[BillConn]

Thanks men - it's the first of a series of articles about using diagnostics, and there will be a video to go with them.

The method we used here for setting the carburettor needle height (on two-stroke Villiers motorbikes) was to go absolutely flat out and jam the rear brake on to stall the engine - and then pop the spark plug out to see what colour it was! We moved on to the glass Colortune spark plug to see the combustion colour in real-time but just got continuously electrocuted......

Edit, just searched and they still make them:

https://www.ebay.co.uk/i/13075800424...8853793&crdt=0

As others have said! fantastic effort Timm! I've used your site many times and this article is an AMAZING addition.

[Timm]

Thanks again, video added as promised:

https://youtu.be/CBfyCItOJH0

[Aitch]

Thanks again, video added as promised:

https://youtu.be/CBfyCItOJH0

Awesome work Timm.

Also - your E31 looks amazing.

[kouks]

Thanks Timm, I’ve been chasing a rich condition on my e34 M50 TU and this will help. Runs like a top, but barely passes smog, no lights, rebuilt the engine a year ago and still no change.