Ok so I've been fighting this SES light for a while. I have an 06 MCS with 69k on it only mod i've done so far is a 15% reduction pully (done at around 64k) and a DICE Ipod controller (it plugs into the car so its getting mentioned lol)

My problem is when driving on the highway the SES and the EML light come on (occasionally the DSC light too?) When I get the codes scanned it says 1125 and 1687. From what i've found on the web that's the throttle position sensor fault and some diagnostic for it. This problem only occurs on the highway though and once the light comes on I have to pull over and turn the car off and back on to get it out of limp mode. Doing so clears the EML light but the SES stays on and I can continue my journey. So far one time pulling over does the trick and it won't come back for the rest of the day (longest i can remember ive drove after is about 300 miles). Also after a few starts on the engine the SES light will finally turn off? i've had it scanned shortly after the light cleared itself and the codes are still in the computer. doing a search brings up 2 possible culprits either my engine harness or the throttle body both which are fairly expensive. Is there any way to pin point which of the 2 it is without throwing money at it?

Also another note I don't drive on the highway very often (past months vacation is really why I had been) but my daily commute I cruise around 65 on the fast country highways (whatever they're called) so there is only a difference of around 10 MPH.

any help would be great. i've noticed a couple TB's for sale on the market place that would save me some dough but would rather know if that will fix it.

 

Have you dont anything about this yet? I have a similar problem, and I 'm also stuggling to pin point it!

 

The throttle body does have a servo on it that moves in conjuction with a sensor on your accelerator pedal (i.e. drive-by-wire). Not sure which one could be the culprit. My guess is, whichever one is bad, there is a synchronization issue between the two.

On a side note, the TPMS light is not related. I'm beginning to suspect you may a battery that is slowly dying. Get the voltage level checked.

 

Still having the issue except now it seems to do it whenever. back roads or highway it can still come on. Not sure what to change the harness or the throttle body... I may just ride it out until whatever it is breaks completely it really has no constant effect when it does act up. My only concern right now is getting it to behave long enough to pass emissions (I have till June of next year ). But it seems once the code drops off the ECU it pops right back up again. So it may be constant... just doesn't appear that way to me. Think I see a scan gauge in my future.

on another note not sure why I said TPMS was turning on. It was Actually the DSC light (I corrected my original post).

 

Any update on this issue? Had the SES, EML and DCS lights out of the garage this morning. Cycled the start sequence and got two blocks from home before having to limp home. I'll be busting out the OBD reader as soon as the OAT drops below 100!

tm

 

I responded to another thread about the P1125 code:

It is possible the terminals in the harness plugs are dirty or corroded. Unplug it and check for signs of this. If dirty, clean with a can of compressed air. If corroded, the male ends should be easily cleaned with a brass brush. The female ends will be a bit more tedious. You will need a round jeweler's file. You should be able to find a set at an arts and crafts or hobby store.

Beyond this, it's possible the harness is defective and needs to be replaced.

 

I am having the same P1125 code problem with my 03 MCS over the past few months. The first rash of it happened every 3 to 10 miles, 4 to 5 times. I had unplugged both the computer end and TB end connectors so the contacts get wiped. The code still came back. Cleared the codes and then did the following reset at the end of this post by agoodsign:

"Actually, I meant to post an update, we finally fixed the problem. There are apparently two potentiometers in the TPS system that need to be in sync with each other, on reads somthing like 1-7 volts and the other 7-1 volts in reverse (I can;t remember the exact voltage), they need to be balanced, it's a fail-safe system to make sure the ECU knows where the throttle position is. Somehow they got out of sync in the car and we just had to find a simple reset procedure for it... Turn the key to the 1 position, hold the gas pedal down wide open for 25 seconds, let off completely for 10 seconds, and start the car and let it run for a while, it'll idle rough at first but eventually it evened out."

This reset worked for me for around 300 miles. I had to take the front end off to replace the water pump, which included disconnecting the TB. After putting it all back together this P1125 code set again a couple days later, multiple times. I have cleared the codes, sprayed the TB connector and computer connector with electrical contact cleaner and done this reset. Code has not returned in 35 miles so far, but I'm losing trust. May have to replace the harness as indicated in SIM 12 04 02 (TSB from march 2006) But my car has 97K miles so it could be the TB???

I work in the electronics industry and don't recommend using a file on these very delicate gold contacts. The gold is typically 30 micro inches thick so a file will tear it up, increase the resistance, and reduce contact life. Use a spray cleaner for electronics and try this wide open throttle reset...
-dan

 

I have actually tried that reset before... maybe I did it wrong because my car never idle'd rough or anything. I am also in the electronics industry filing didn't seem like a good idea. Ive used DeoxIT on the connectors and that didn't seem to help. The past couple days my car has been really acting up (4 times in 2 days) which isn't very common. Perhaps the issue is worsening which should lead to finding the culprit. I was thinking about it today thought the course of my issues and one noticeable change I can think of is my problem went from being a consistent highway only problem to happening whenever. And it seemed to do this when I did the VGS mod to my bypass valve. I also cleaned the TB when I did that mod maybe it is the TB and I degunked the only stuff keeping it from really acting up. I find it hard to say it is the engine harness my car has 72k on the clock wouldn't this problem have come up a long time ago... although I bought it when it had 62k and I only first noticed it around 66k? perhaps the previous owner ignored it all along and now it is my problem. Although I did do a reduction pulley within the time frame maybe that could have something to do with it? Either way both the TB and the harness cost around $300 so I would really like to pick the fix and not have to dish out $600 in the end.

I will be removing the VGS mod this weekend and cleaning the connectors again.. gonna scrub them with a nylon brush maybe the will help loosen any possible crud.... Will update if this seems to do anything.

 

I'm with ya on the pick the fix for $300 instead of $600 in the end. Did you clear the codes before you did the wide open throttle reset. The reset didn't work for me until the codes were cleared.... but I also spray cleaned the connectors and then did the reset, so maybe just handling the connector affects it. My car is a 06/2003 build, which is within the last month of when the TSB says, in the end, replace the harness. TB has a build date after the bad window. Your 06 should not have the poor crimps on the connector pins, and TB should be good, but can't rule it out entirely. I'm now 80 miles code free. With 97K miles I'm leaning toward the TB. My car is completely stock too.

 

I did not clear the codes before I tried that, guess I will have to talk to my friend who works at auto zone (kinda out of the way). cause no one else around here will clear codes for me . Never really understood that I guess its a liability on their part if they clear it and my car blows up or something.

 

It's gotten worse, code set at 110 miles since clearing, then another 140. Now I feel frequent hesitation, getting worse. I won't drive it to work anymore, driving the backup....

 

sorry to hear it has gotten worse for you... I've been meaning to post an update on mine here. So I removed the VGS mod and my car drives a lot different (for the better) i don't feel the yo-yo sensation anymore but the extra umph at the top end seems to be gone (maybe my perception) I also gave the TPS connector a good look over and looks clean and the pins look to be fine (not enlarged etc) I gave them another hit of Deoxit and brushed it a bit...

I got around 280 miles before a check engine light. Once I got the light it happened probably about 4 more times with in 100 miles... but the difference this time is it only happened on the highway again. It seems by removing my VGS mod the problem returned to where it always was. which was a highway only problem. I'm starting to lean more towards the throttle body as the culprit.

I think I'm now on 300+ miles since the last occurrence. I suppose it's because my lack of highway driving recently. I did however notice that from what i've been observing is it only acts up while cruising around 70+ which is right around 3k RPM I will be trying to avoid that zone for a while and see if that helps the code not appear (not really a fix but a controlled environment kinda)

sorry if this seems like a whole bunch of rambling kinda just typing all the thoughts as they come.

 

The MCS became undrivable. I could feel lots of hesitation. It would go farther between P1125 code sets if you vary the throttle a lot. Constant pedal movement. But finally parked it to figure it out. too unreliable.

I have diagnosed my problem to be the TB. The manual has a schematic of the potentiometers inside the TB on page 130-20. It is basically 2 resistors, around 2K each, in parallel with a wiper to each one. As the butterfly moves one pot will go up and the other down in resistance relative to the ground or supply inputs.

Much easier to test with the TB out and you may need a second person if you don't have small alligator or J-clip test leads to connect to the TB connector pins and your ohm meter.

Measure between pins 2 and 6 and get around 1000 ohms. This is two 2000 ohm resistors in parallel.

Measure resistance between pins 4 and 6. I got about 1300 ohms. Very slowly push the butterfly open and watch the resistance change down to about 450 ohms at wide open. Let it close. Change leads to measure pins 4 to 2, mine read 620 ohms. Slowly push butterfly open and watch reading increase to 1300 ohms, at wide open. If you get readings like this then the potentiometer at pin 2 is good.

Repeat the above procedure for pins 1 and 2, then 1 and 6. The most important part is the resistance changes in small increments in response to small changes in butterfly movement! watch for large jumps, and it going open circuit.

For my TB when measuring between pins 1 and 2 I got about 1500 ohms, then with very slight pressure on the butterfly it jumped 600 ohms, then at about 10 degrees rotation it went open circuit, which it should not do. This also makes sense when driving at a constant pedal position and you just happen to hit the position on the potentiometer where the resistance makes a big change, then the codes sets because the two pots don't compare.

Just ordered a TB from DDM Tuning for $231 shipped as it's on sale now. BBA-Reman said they can get your TB rebuilt but I didn't have my TB number to get a quote. They had just done my power steering pump.

Hope this helps,
-Dan

03' MCS

 

The new Throttle Body fixed it!

 

dhogan, glad to hear it's fixed.

 

glad to hear yours is fixed I currently havent had a code in over 1500 miles now... I guess until my issue gets to a constant problem I may just wait it out. oddly enough I kinda predicted with the colder weather the code would go away and so far it has. Either that or my last cleaning I did on the connector did the trick.

 

Well up until 2 days ago I haven't had any issues with my SES light coming on.... Now the past 2 mornings (coldest we've had here in GA) I have had a light come on pretty much anytime I lightly hold the gas pedal (maybe not right away but within a mile) My guess is now with the cold the coils are contracted bringing the problem closer to my back road driving range. When before this was really only an issue of warm weather on the highway issue.

Besides all that I had 2 new codes accompany the 1125 which bring a little concern to me I have a P0123 and a P0222 they are pedal high/low positions. I'm not sure if these were old codes from when I tried unplugging my TPS and starting the car or not (that was over a month and 2k+ miles ago) and I'm pretty sure I cleared those right after I did it.

I know the P0123 and P0222 happen when the TPS is disconnected, the car also Idles really rough when this happens. During my several codes on my ride to work (over 6 if I had to guess) The car never appeared to idle rough then again I didn't pull over to restart my car (just popped the clutch)

Besides my long story here what do you guys think should I just suck it up and buy the throttle body? Or am I wrong and could this actually be the engine harness? I was hoping to pull the trigger as early as possible so I can get the part here right away.

 

So I haven't ordered the new TB yet because I wanted to try dhogan's measuring method.. after doing so this morning I conclude that My TB is junk and i'm wondering how the hell my car even drives.. here are the results

Pins 2-6 : 1.25K
Pins 4-6: 1.543K (closed) 599ohms(open) while getting to open the resistance goes up to about 3k goes open then a little more open on the TB and resistance comes back and continues to go down...
Pins 4-2: 700ohms (closed) 1.578K (open) does about the same as above.

Pins 1-2: 1.8K (closed) 630 ohms (open) While testing the range it does similar to the first coil it the resistance increases to about 3K then goes open and comes back around 2.4K and continues to go down.
Pins 1-6: 990ohms (closed) 1.7K (open) similar to above but it gets to 3.6k before it goes open and comes back in at 2.2K and continues to progress to the 1.7K at wide open.

the above results had me shocked I measured them twice, regardless of the resistance on both coils mid range I could find a sweet spot where the resistance goes open... perhaps because both coils appear to be semi equally screwed up perhaps that is how my car is able to chug along? either way I will be ordering a replacement today.

 

Jeffster06,
It definitely looks like your TB is bad on both pots. I measured my new one and the resistance never jumped unexpectedly. It closely followed my moving the butterfly between the high and low readings at each end. I have put 4K miles on the new TB with no relapse.

If the other codes keep coming back it and you have not been unplugging the TB then it could be your pedal assembly.

 

So far my car has been driving fine no SES light on (but then again it never was constant). I am having a new issue with my EML light turning on. When I scanned the code it comes back with a pending 1498. I believe this code is for a vacuum leak. So far to fix this I have removed and reinstalled the TB. The light will still occasionally blink on. I've noticed it only does this when I'm on and off the clutch. Like when backing up, pulling into my driveway slowly, or moving in stop and go traffic. There is absolutely no performance decrease with this though (no limp mode). I have a feeling the vacuum hose on the TB may have a pin hole leak (took a lot of force to remove and has some dry cracks on it) that will probably get worse as the temperature rises. So far I haven't seen this issue come up in temps lower than 40.

I will be sitting on this problem watching how it behaves with warmer weather. If I'm correct it should start really misbehaving when it gets warmer out.

 

Yes, it did help. A lot!

I suddenly went into limp mode at 75mph on the interstate this past Thursday heading for Orlando. Pulled of at the next exit, found a parts store, and got it scanned. P1125. Continued the trip with a rental car, but on the way back home, felt much more comfortable driving the Mini home, knowing what the problem likely was. Didn't hit limp mode on the way home since I took back roads instead of the interstate. Nice.

I picked up a new throttle body at the Orlando Mini dealer. $350 with tax. Ouch, but I had to get it back on the road this weekend. Pulled the old one and both pots were bad in a couple of areas. The new one had a smooth resistance curve all the way.

Thanks for the easy diagnostics, dhogan. I have the manual, but your post made it an E-Z check.

FYI, in case anyone is tracking when TB pots fail, 06 Cooper S with 113k miles.

 

Thanks for the info, guys. I had an intermittent yo-yo problem on the highway for awhile, as well as a litany of other problems (slipping s/c pulley, VGS gone awry).

I took the TB out and tested the pins as dhogan suggested, everything more or less checked out, but pin 2 jumped from about 2k ohms closed, to about 750 ohms open, with no change in resistance from closed until about half open.

I replaced the throttle body, and that seemed to fix it. I got a P1125 and P1126 as well, when I installed my Helix 450cc injectors and suspected it was the canned tune for my Unichip. Hopefully it was the throttle body all along.

For the record, the car is an '05 S with a build date of March, 2005. 89,753 miles.

 

I had my TB replaced recently on my '06 MCS, 57K miles. Similar symptons for quite a while, yo-yo, slow response, multiple SES lights (usually indicating a mixture too rich), the car was not at all fun to drive. Then had full out EML light, limp mode and codes. TB dead, tech also replaced the MAP sensors to deal with running too rich. Cars hasn't ran this good in 2 years.

 

Anybody have the pin layout for the meter test?

Thanks,

JT

 

My '06 MCS with just 62k miles on it has the same kind of problem I'm reading about here. For no apparent reason it goes into limp mode, but will run ok if I stop, take the key out, wait a few, and restart. The code P1125 always comes up. My shop has changed the Throttle Body, the Throttle Position Sensor, and the Crank Sensor, but I still get into limp mode almost on a daily basis. The shop has given up. Any ideas?