I ran codes for my '05 R53a and was given an overwhelming laundry list... I have researched all of these issues on NAM and other MINI sites, but really I need some direction on what to tackle first. I am at also 180xxx miles.

Some backstory: The totality of my issue really began May of 2019 when I was driving back during hour four of my six hour trip on I-20 and my OEM factory-original cat converter did what seems is a common occurrence and snap in half at the weld. The car instantly become almost unbearably loud and when I finally got back home, I parked it for the next two months without driving past the edge of the driveway. Money has always been a little tight for me, so fixing issues with my projects take a backseat. Fast forward to August and my brother went to move it so he could do yard work and discovered that a little field mouse decided to turn my engine bay into a home and made a nest directly on top of the throttle body. Oh, and in its spare time, it loved to chew on my wiring harness and the heat shield for the hood. I replaced the wiring harness with a used one off an '06 R53 and also replaced the MAP sensor that by the thermostat housing. I used a BMW Genuine sensor.

Fast forward another three months... car is still sitting, but have moved it a concrete slab (my back porch to be accurate). Now it's time to move to my new home about a nine mile drive way... And I made it to the end of the driveway. Interior lights went crazy and I knew the battery was toast. Repalced the battery, started right up with a little blinking from the interior lights, and the car drove and accelerated great... of course still loud as a banshee leaving Hell. I did noticed that any time I had to stop, the car would idle horribly, RPM's ranging from 700 to 1100. I had to hit the accelerator a few times just keep it from dying which of course made the locals think that Brian O'Conner was moving to town. A few dirty looks from the ole timers. Got to the new house and parked the car in the driveway until three weekends ago. I was FINALLY able to buy a Megan Racing header w/ test pipe that I have for now bolted up to the old OEM catback and installed two new aftermarket oxygen sensors as well. I had to cut the raised plastic areas out of the sensors because they did not line up with my female plug. I got bank 1 and 2 to clip into the female connector, but I am wondering if maybe this is a part of my problem that I will detail later.

Also, I had a TERRIBLE oil leak from the cam and crankshaft position sensors and was seeping up around where the dipstick tube meets the block. I replaced both sensors with BMW Genuine sensors, followed the Easy-Off with a pressure washer method of getting the caked on oil off the block, and applied some high-temp sealant around the dipstick tube to seal. Not sure if it matters, but I do have a Cravenspeed flexible dipstick. The only area where I seem to still have some leakage is around the area of the drain plug.

After I got the oil leak repaired and got the new manifold installed, I started the car and OH MY GOD I fixed two problems and I gained four! The RPM's were bouncing all over the place, ranging from 750 RPMs to 3500 RPMs. The RPM's would stick and then start fluctuate... and then stick. Also, my stainless steel header began to glow orange. Not slightly red, but from the block to the test pipe ORANGE. I also have a squalling noise coming from the passenger side of the engine. Quickly turned off the car and let it cool down, but the exhaust was significantly quieter and I had no exhaust leaks. Had my brother pull out his trusty OBDII reader and gave me a laundry list of codes. They are as follows:

- P1777 - ABS/wheel speed sensor
- P0700 - Transmission control system malfunction (from what I've read, this just the TCM telling ya there's something up)
- P0340 - Camshaft Position Sensor "A" Circuit (this one confuses me because I replaced the cam sensor)
- P0420 - Catalyst System Efficiency Below Threshold
- P1229 - Throttle Potentimeter
- P0123 - Throttle Position Circuit "A"
- P0223 - Throttle Position Circuit "B"
- P0036 - HO2S Heater Control Circuit, Bank 1 Sensor 2
- P2270 - O2 Stuck Lean, Bank 1 Sensor 2
- P1477 - Vacuum Issue (I believe I fixed this one. I forgot plug a small vacuum hose into an elbow located by the left side of supercharger & fuel rails.)
- P1109 & P1242 - Manifold pressure related. I read this can be caused by the intercooler boots not seated properly. I have adjusted the boots, but have not checked to see if code has cleared.

Also to add, the battery in my sister's FIAT was acting up, so I donated my new battery to her. I took hers to Autozone and had it checked and charged. The battery held a charge, but was at 11.5 volts before taking it to AutoZone. I put this battery into the MINI after completing my repairs.

To recap what I have replaced:
- Wiring harness with used harness from an '06 R53a. I made sure it was for an automatic and no broken female connectors.
- MAP sensor by thermostat, camshaft and crankshaft position sensors with BMW Genuine sensors
- OEM dipstick with Cravenspeed dipstick
- OEM exhaust manifold with Megan Racing manifold with test pipe
- OEM oxygen sensors with aftermarket, non-genuine oxygen sensors... budgets suck.

I have never been to a point with any car I've owned where I just wanted to push it off a cliff and be done with it, but I'm getting close with this ole boy. I am so overwhelmed at this point; to think I'm making progress only to be slammed with another to-do list from the bastard. I'm also getting to a point where I NEED this car running. I'm about to sell my Jeep for financial reasons and I need Berndog rolling.

Really what I am posting this is for some guidance, what repair I should start with, and some insight on these codes. A lot of them are related, but I cannot afford to just start replacing everything. Where should I spend my money first. The wheel sensors are cut and dry and I have dealt with the trifecta issue in the past. For the codes exhaust related, is this because of the non-genuine oxygen sensors and/or because I'm running catless? Should I consider having a high-flow cat fabricated in (my county does not require emissions testing)? Is this why my manifold was turning orange (this scared the bejesus out of me)? For the throttle body codes, does this mean the throttle body needs replaced or are there other things to look at? I researched every one of the codes and picked up a few pointers, but I want to do the repair that will make the biggest impact first. I've been working on my own vehicles for 15 years now and I have completed all sorts of repairs... and am use to successful repairs. I would put my experience level at intermediate.

Help a fellow enthusiast out!

 

Well I am happy to say that my Cooper S is back on the road today and is code and light free! The only lights that are on is for the airbag and tire monitoring... a huge win in my book!

What I replaced in whole:

- Both cheapo o2 sensors that I put on for a pair of the NTK 25648 sensors, I think this made the biggest difference.
- Replaced the half-dead H5 battery with an Everstart Platinum H6 battery... perfect fit!
- Replaced cracked OEM exhaust manifold with Megan Racing header w/ test pipe
- Passenger side wheel speed sensor with a Delphi speed sensor. Old one had worn down to the wire... must've been rubbing on the wheel.
- Old idler pulley for a new one
- Original intercooler boots were ripped and swapped them out for the M7 speed silicone boots. Nice, snug fit and look great!
- Reattached small vacuum line located underneath intercooler on passenger side
- Replaced camshaft, crankshaft, and MAP sensor
- Swapped out wiring harness

I do find it strange that I am running without a cat, yet the P0420 or any exhaust-related codes have not presented themselves... they may come up later but I digress for the day and will take win this to the bank! Also, my header isn't changing color at all. Neon orange was a huge concern for me, but the header is staying cooler even after a 15 minute spirited drive. The only issue currently is a small oil leak coming from the backside of the block which I've narrowed down to the oil filter housing gasket.

Thanks to the YEARS of threads that have accumulated on NAM for aiding in my search for info. It helped a lot.

 

Sounds like a win to me. Congrats dude!