[ssbourbon1]

Has anyone else had this and does anyone know were it's located/how to replace the exhaust pressure sensor if within reach? Help, don't like driving with the CEL on

Thanks, Scott

[Yozh]

Can you post a description of the fault? Pressure sensor is not difficult to replace.

[ssbourbon1]

This is what a general website says about it. Also what ORielly's guy said....

Generic OBD Error Code Details for P0471
Exhaust Pressure Sensor Range/Performance

More from the site...

OBD Code P0471refers to
The exhaust back pressure (EBP) sensor is a variable capacitance sensor that, when supplied with a 5-volt reference signal from the Powertrain Control Module (PCM), produces a linear analog voltage signal that indicates pressure. The EBP sensor's primary function is to measure exhaust back pressure so that the PCM can control the exhaust back pressure regulator (EPR) when needed.
Symptoms
Possible sumptoms of OBD code P0471
- Engine Light ON (or Service Engine Soon Warning Light)
Causes
Possible causes of OBD code P0471
- Exhaust Back Pressure Sensor The Error code is generally activated on detection of the following conditions: An EBP signal that is detected out of range (high or low) by the PCM will cause the engine to ignore the EBP signal and disable exhaust back pressure operation.
Possible Solutions
Replacing the exhaust back pressure usually takes care of the problem

[Yozh]

Ok, you are in the US and I assume you have all the emission parts intact and not modified. If otherwise, please do post.

There are two possibilities here. One is yes, your sensor may be bad. Two, you have an exhaust system blockage. If so, then most likely your DPF is stuffed. Before you go about buying a new sensor and trying to replace it, you need to eliminate the possibility of option two, which is your exhaust system blockage.

You need to do some diagnostics first. You got this P0471 code from somewhere, obviously. As a start, what would be good to do, is to see when was your last DPF regen. You can do that with any BMW specific diagnostic tools. If you do not have any may be someone local can assist you. DPF regens happen about every 400 miles. If you know how to spot one, may be you have been monitoring them, or not. Also, would be good to pull any pending codes, with a BMW specific tools that is. An increased exhaust back pressure may also trigger a pending or a full code for increased exhaust gas temperatures. Basically, here, you need to eliminate the possibility of your exhaust being plugged.

[ssbourbon1]

Thank for the starting place Yozh. Yes my system is stock. I take it that when you say use a BMW specific diagnostic tool you mean BMWhat? I do see the regens from time to time when looking at my miles to empty numbers suddenly to drop and come back but I don't always pay attention to that. Will the BMWhat tool show me what you are mentioning?

Thanks again. Scott

[ssbourbon1]

OK, I got the BMWhat app and a blue tooth OBDII connector.....and the more detailed results are as follows:

Engine / Motor
Fault: exhaust pressure sensor
Code: 48D1
Fault: Air system, EGR
Code: 4862
Fault: exhaust pressure sensor
Code: 4990

I cleared them once and two days later the same ones came back

Any ideas? Thanks for your help! Scott

[floydarogers]

As stated, some problems with the DPF and whatever.

There's a hose that goes from the DPF to the pressure sensor, and the pressure sensor: parts 6 & 9 http://www.realoem.com/bmw/showparts...87&hg=13&fg=15
They're just visible near the right rear of the engine near the cover. Check them to see if it's burned through.

Bad news if the DPF is plugged; expensive.

[ssbourbon1]

Thanks for the location of where to look for the sensor itself. I'll check it out weather permitting. Also, I'm waiting for the BMWhat obdII blue tooth adapter so I can monitor the exhaust temps and pressures and see about the regens. I know that MPG to empty suddenly will go down and haven't been looking at that, also haven't driven too far lately. I'll be driving a 400 mile trip on Monday will see if it's happening. I'll keep digging....and saving up some cash for the potential repair.

[Andrewah05]

When I got this I had to.get.my.cats replaced but BMW had like a 8 year warranty on emission components

[Yozh]

Scott, this fella in the UK had a similar issue.
http://www.e90post.com/forums/showthread.php?t=1090887
I am not sure if filling up or not makes a difference, but something to watch.

Also, how often do you hit the highway. If you are always in the city that may also be a problem with a lot of stop and go and partially completed regens. Some people had success with doing a forced regen. That one has to be done through diagnostics and I am not sure BMWHat has it active yet. Or hit a good long highway trip and regen would ensue. Now, if you run with a SES code and you are going for a 400mi trip, you are brave man, I probably would not do it. DPF replacement is probably your last and most expensive option before you try everything else.

I also would like to draw your attention that when we talk about exhaust pressure sensor and exhaust differential sensor, these are two different things. Exhaust pressure sensor is a sensor that is picked up just upstream of the turbos, measures, exhaust backpressure. Exhaust differential pressure is a sensor that is specifically for the DPF and picks up just before and after DPF to measure the load on the DPF and is one of the parameters to determine when to do a regen. Actual sensors are housed on the panel just above the turbos on the passenger side of the engine. I'll see if I can find a picture to show you where they are and they are both fairly easy to get to. But I would not get there yet.

floydarogers posted the right link for you. If I may put the pictures of the same to clarify:





Both sensors are attached to #1.

Exhaust pressure sensor is #6 feeds from tube #9 that attaches via a banjo bolt #10 on the manifold between two turbos.

Exhaust differential sensor is #3 fed by two hoses #5 off the DPF. These two hoses are not secured in any way except by friction. Sometimes they may fall off or burn through as floydarogers mentioned.

These two you need to check before departing on your trip. If the front one is off, you will smell exhaust in the cabin, if the back one falls off that may not be the case. To check, you can just take a good flashlight and look or remove the engine cover, air box, and then you can fix them back on. If your exhaust back pressure is too high the front one may fall off again.

[Yozh]

[ssbourbon1]

Yozh, you are the man! It amazes me what you can find....

Just a few notes to follow up on what you were saying....My D is primarily driven on the highway (about 70% of is use). 99 times out of 100, I fill the tank to the top. However, the day that this code first showed, I had put only a few gallons in as I was going to be crossing the state line to SC where Diesel is $0.50 cheaper.

The car hasn't seemed to have lost any power at any speed, no smell in the cabin from fumes either. When the weather settles down here, I'll get under the hood to see if any tubes are off in that area. Your picture and description will make this easier.

I'll see how it goes on my trip on Monday and just fill up the tank frequently so it doesn't go under 1/2 tank. Not worried about driving with it. My trip on Thursday this week was almost 300 and the code didn't show up, but it did when the tire guy started it up yesterday putting on new tires. Seems only to be at start up not while driving.

[Thecastle]

Originally Posted by ssbourbon1

Yozh, you are the man! It amazes me what you can find....

Just a few notes to follow up on what you were saying....My D is primarily driven on the highway (about 70% of is use). 99 times out of 100, I fill the tank to the top. However, the day that this code first showed, I had put only a few gallons in as I was going to be crossing the state line to SC where Diesel is $0.50 cheaper.

The car hasn't seemed to have lost any power at any speed, no smell in the cabin from fumes either. When the weather settles down here, I'll get under the hood to see if any tubes are off in that area. Your picture and description will make this easier.

I'll see how it goes on my trip on Monday and just fill up the tank frequently so it doesn't go under 1/2 tank. Not worried about driving with it. My trip on Thursday this week was almost 300 and the code didn't show up, but it did when the tire guy started it up yesterday putting on new tires. Seems only to be at start up not while driving.

Yes bringing this back from the dead. Since I too have 4862 and 48D1 on my car along with a 3eed error, I wanted to see what fixed this for you. I just had my egr cooler replaced, and fixed a second time because the mechanics at the dealer snapped the bolts holding the egr cooler on at the exhaust snapped. All fixed under warranty, however warranty ran out Jan 31st

So I'm getting diesel fumes in the cabin, and an inspection turned up nothing obvious. I'm still getting a 4862 and 48d1 error and ses light that is on and off. I wanted to learn how you fixed this.

[BB_cuda]

Advantage Clear Lake did this? Check to see if differential pressure tubes are loose on either sensor end or on DPF end. Item 5 (2 of them) in yozh's post #10. Other source of exhaust smell might be exactly where they broke the bolts at (exhaust/EGR cooler interface).

[Thecastle]

Originally Posted by BB_cuda

Advantage Clear Lake did this? Check to see if differential pressure tubes are loose on either sensor end or on DPF end. Item 5 (2 of them) in yozh's post #10. Other source of exhaust smell might be exactly where they broke the bolts at (exhaust/EGR cooler interface).

Yes, the egr cooler on my car failed by cracking and leaking coolant. I took the car in before the warranty was up for a 4862 error (no ses) and a 3eed error. The dealer diagnosed it as a cracked egr cooler and replaced it under warranty.

Last week i still see the 4862 code pending, and had a strong smell of diesel fumes in the cabin. So I took it back and the dealer said that the bolts holding the exhaust side of the egr cooler had broken. They weren't sure how, they claimed to have used a torque wrench to tighten and no air gun. Replaced the bolts under warranty.

This weekend I drove to Austin, on the way back an ses light illuminated, 4862 and 48d1 showed up, and I as smelling really bad diesel fumes inside the car while driving. Drove it home on recirculate with a window cracked. The little car knew I was investigating and turned the light off again., this afternoon.

Checked it today and I didn't see any loose pressure tubes, I checked. Exhaust fumes are definitly coming from the area near the exhaust side of the egr cooler. Bolts look fine, I may pull the air box and take a look, waving for the engine to,cool. I'm thinking I should just install my egr block kit and be done with it. But I'd hate to have a bad cooler if I want to reverse this later and sell the car.

I'm also concerned something else isn't right besides the egr cooler. But I don't wanna pay the stealer to fix it. I suspect if there is a problem with cooler install they'll take care of it.

[Thecastle]

Just a quick update on this. I pulled the intake and notice soot around the accordion section of my egr cooler here it attaches to the exhaust. Took it back to the dealer and they verified the new egr cooler is bad. So it's being replaced again, at dealers expense. The dealer noticed the replacement egr they installed under warranty looked dented nut didn't expect it to leak. So they are replacing it for free again.

P.S. This will be the 3rd egr cooler replacement this car has had, 2 were replaced for cracking, and 1 bad install/manufacturing defect. Also the EGR valve has been replaced 3x., once under my watch. I think this car is a good candidate for a block. I just want to make sure the hardware is in good shape, so if I reverse it when i sell, the hardware will work as expected.

[Thecastle]

finally fixed the two errors.

For me it required a replacement of the exhaust pressure sensor (#6 above), and my EGR cooler. That eliminated the error's for me. Just putting this here for future reference in case anyone else has this same problem.