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BMW 3-Series (E90 E92) Forum
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Shops cant figure out Exhaust Gas Pressure Codes
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11-19-2018, 01:20 PM | #1 |
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Shops cant figure out Exhaust Gas Pressure Codes
Hi, new here but I use this place all the time to find issues. I have searched and found a method here that seemed to work but let me explain.
2009 Bmw 335D - Stock 145k miles A few months ago I had a code #4990 and a mass airflow code and had taken my car into the shop as my pulley had broke. I had that fixed and had them look into the rest. They said they think it's my intake manifold build up. I had them fix that as it was pretty bad anyway. That didn't fix the code. So I brought it back (this is a BMW and Mercedes shop) and they said: "This is rare and unlikely but we can replace the exhaust gas pressure since before the turbo." So I let them do that and two days later, the code was back. I looked on this forum myself and found that the exhaust gas pressure LINE can plug and sure enough, it was plugged solid. Long story short, I cleaned it with the coat hanger method but lost a copper washer so I made one from a soda can so I could get my son to school. (wasted $40 on Uber to get to a parts store and they didn't have the right one. I called ahead, they were just wrong.) It worked. No codes for 6 weeks. I figured if it came up, then the washer fired and ill replace with a new one. Well, two months later it was back so I did just that. New line and washers. When it came back I also had these 4D97, 4990, 4B7f, 4687.... Not only that but yesterday and today I even got the engine light (picture) and it said "Engine Malfunction! Reduced power. Still operable. See BMW service soon." I took it to a new shop that does German cars and he said to contact the dealer first for service bulletins. Seems like the 4b7f code is the main code now as I can delete them but that one comes back instantly and shortly after is the 4990. All three of those codes point to the same thing. they are range, signal, and plausibility. I am waiting on the dealer service advisors to call back. The only other video I found was an X35d mechanic showing something with the vacuum system that causes it. I don't want to keep paying money for the wrong thing to be fixed! I am hoping I am just searching for the wrong stuff on here and its a common code occurrence with this series and it will point to a simple part change. Any information? By the way, I use the c110+ scanner for BMW. |
11-19-2018, 01:45 PM | #3 |
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Also, this is the only service bulletin I can find and it has to do with the DPF regeneration. First link is a PDF.
https://www.google.com/search?rlz=1C...71.PDM1UXvlx08 |
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11-19-2018, 05:31 PM | #4 |
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Also, I used my scanner to check the data stream on the particulate filter section but it defines it as "Difference exhaust gas pressure" and the 'mbar' (i don't know if there is a difference between M or m.) is over 22,000 at idle and 23,000 at 2500rpms. The videos I see show them in the 300 range when they are plugging but they have a capital M on Mbar so I'm not sure if mine is a smaller measurement?
I am typically driving 20 min - 25 miles to work on the highway every morning. Not too cold out and fully warmed up car at 75mph. I just put some Liqui Moly DPF cleaner in the fuel and have 4 more cans I will try and run. No one has any idea yet that's read this? |
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11-19-2018, 07:10 PM | #6 |
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I'm in california. Rip everything out, smog shops generally just test for smoke out the tail pipe and that your monitors are cleared, which should be handled by the reflash.
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11-20-2018, 12:47 AM | #8 | |
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Quote:
I called a shop here that deals with big rigs DPF's and they bake them clean. They said they have done plenty of my cars as well with the M57 motor and its a very high success rate. usually, they come in around 120-160k they get them about 95% cleaned out. They just won't remove it from the car so you have to do that yourself and is only $250. I'll talk to their tech tomorrow. The other option was the liqui moly kit for $400 to clean the DPF and I don't have to remove it. Looks promising. Watched a few videos on it. 3rd option would be like Dr. Rockso said and take it out, reflash, and hope smog tech doesn't notice on inspection. I did this with my cat on my Jetta but this would be very obvious. I would rather find a used DPF and gut it and weld it back together. I don't know man. I might just buy myself this VW Golf TDI, clean the DPF and sell it. Too bad because I really enjoy the power and style of this car. Its a nice, sport model with the 195 wheels. But it would be nice to have something with 20k miles to bot worry about breaking down with my kid. Ask me how I know that. The cleaning company said when those pressure codes are coming, it's plugging up and eventually, I will get the DPF code. I have had it a year ago and it went away. It would be nice to keep this car for another 150k miles and not have to dump a ton of money into it. |
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12-03-2018, 12:23 PM | #9 |
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Ok. I am back with new information. Still need a little help and also want to post for future users. I replaced the DPF (what a nightmare!!) with a used one that had 70,000 miles on it. Came with all the sensors too. Once we got it on, I still ended up with the same codes BUT there is no "service engine soon" light... Just the "engine Malfunction" light. That's weird. If I delete it, it comes right back. So it wasn't any of the sensors on the DPF as those were used, but all different than the ones on my car so I figure there odds are in my favor there. So basically now when I start the car, you hear the chime and the yellow motor appears where you clock is on your dash, and on my screen it says "Engine Malfunction. Still Operable. Reduced power. Visit service center soon.".... But no check engine light.....
Someone messaged me to check the Differential Pressur sensor to the DPF and both the vaccum hoses are tight and good.. I noticed a tiny shine of copper wire so i was thinking maybe its shorting its reading? But seemed very unlikely as there is nothing to touch around it and none of the other wires were showing. But these are the codes. 4D97 Exhaust Gas Pressure before turbo charger, Range: lower physical limit undershot and 4B7F Exhaust Gas Pressure Sensor before turbo charger, signal: Open or short circuit to ground. Now those are off a PDF i found online for the 335D but my c110+ scanner says the same except doesn't say short or lower physical limit. The EGPS has been replaced and the hose going to it. It was plugged before but thats fixed. |
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12-03-2018, 12:40 PM | #10 |
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Wow kudos to you sir on actually replacing the DPF. Once I got that thing out it was never going back in!
I would check the connector and the wiring to the EGPS before turbo. I assume the EGPS hose wasn't cracked/melted or leaking? If it says the sensor is open/short, maybe the wiring is shorting out somewhere upstream of the connector. |
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12-03-2018, 01:24 PM | #11 | |
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But anyway, i can check around the wiring more with that sensor and see what teh deal is. That sensor is new, but didn't fix the issue last time, as the hose was plugged, so i took care of that and everything was fine for two months. Then it all came back but the 4990 code isnt there anymore after repairing the hose. So im not sure? |
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12-04-2018, 05:05 PM | #13 | |
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Today, I deleted the engine codes after I saw the "engine malfunction" light went away but the check engine light was on with the same codes. neither has come back on the last 20 minute drive but it probably will as soon as I start it later. I'm going to check all the wires tonight. Obviously, the sensors are working so they aren't shot. There is a short (like the code states) or something is messing up the reading. |
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12-05-2018, 09:29 AM | #15 |
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exportedPIDs.csv.zip
This has the extended pids you can import into torque settings just unzip and import the file in the extended pids page of settings. There's a lot of interesting things you can log like differential pressure, which will show weird values at idle sometimes... If the pressure is very low... But driving would show rational values. |
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12-13-2018, 12:27 PM | #18 |
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UPDATE:
Brought my car to BMW for the two recalls (AC wiring and Airbag)... then paid for the diagnosis for the engine code. They said they tested everything. There is voltage to the sensor (5v) but the sensor has to have gone bad. They told me to call the shop who fixed it and have them warranty the part. they also said it doesn't seem to look like a BMW part so maybe that's it? Called the shop and they said for sure they will warranty it but I asked to check and see if it was a BMW part used so i can have some more confidence if it wasn't one. We will see. Side note, ill have to make a new post because my DPF refill light came on two days before and BMW said I have a hard engine code for the SCR sensor.... They said its bad and the tank needs to be replaced.... WTF!!? It was fine when I brought it in? I am hoping when it was low and the light came on that it cause somethinging where the sensor triggered? Because I deleted it, it hasn't come back after I filled the tank.... So i hope it's not the sensors in there or im screwed.. code 4BAC - DDE... it says power to sensor is normal and harness is normal, lines new and clean... DPF is perfect they said so the one i just changed was perfect because it had the same reading... ![]() |
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12-17-2018, 02:12 AM | #19 |
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Deal with your exhaust pressure sensor first. I agree that of you have an error code for a short circuit you should check the connector and wiring. If your sensor is bad and you just replaced it by a shop then there should be a 2 yr warranty if it’s a bmw part. FCP Euro is a great place for parts as they carry lifetime warranty. Buy once and never pay again. Further, original BMW exhaust pressure sensors are not that expensive. If you can do the DPF, you can do the sensor. Make sure you have no pre-sensor exhaust leaks. Like a cracked EGR cooler. Always unscrew that exhaust sensor banjo bolt when hot. Please do check the differential pressure sensor feed lines. You would had them removed when doing the DPF replacement. They are usually well backed on there. Surprised you can reuse. Lastly, make sure you reset your Exhaust Pressure Sensor Adaptations. That alone could be a cause for your code. For your SCR/urea woes. Start with cleaning your urea metering valve. One clamp. Warm distilled water. That may solve some of the issues.
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12-17-2018, 05:01 PM | #20 | |
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I am going to keep the car and try to make this baby crack 200k miles in the next 4-5 years and save some money from buying a new car. Hopefully washing that sensor (if it comes back on) will do the job. Where can I find the Bosch drop in you were talking about? I looked all over the place. |
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12-18-2018, 02:45 AM | #21 |
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Google Bosch F01C600251
I’m not sure it contains a level sensor inside. I think they do. I need to check my BMW documents. But you also can search around here as it’s been covered. And there is a VW part that fits. Also there us cheap resistor method. A few bux. Mind you I think those are for the heater code and I think yours is for level. Other thing to consider first is to flush your tanks and refill with fresh urea. It crystallizes and renders sensors u usable. Fresh start may free them up. |
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01-29-2019, 05:23 PM | #22 |
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Hey guys. Just to close this thread, it's FIXED! It was the sensor they replaced and was covered under warranty. At least we think it was the sensor as I haven't got a light in 300 miles. They said all the numbers on the machine were coming out fine so they weren't sure what the deal was but they replaced it anyway and reset the monitors and readings. as for the level sensor, someday I will fix it if it remains a problem. So, Exhaust Backpressure Sensor before the turbo.
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4687, 4990, 4b7f, 4d97, exhaust gas pressure |
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