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2005 E320 CDI - Code P0193 - Fuel Rail Pressure Sensor

41K views 22 replies 6 participants last post by  Josh8loop 
#1 · (Edited)
(See page 2)

So my 2005 E320 CDI with 163,000mi is running funny, faltering, sputtering and every once in a while stalling when slowing or at idle, runs fine but weak acceleration on the freeway. It started with infrequent instances with NO Check Engine Light (CEL) on, but eventually CEL appeared and now it constantly runs poorly. The car starting going into "Limp Mode" with a rev limit of 3000, slow pick-up, etc.

Sounded similar to Mass Airflow Sensor issues I've read about here, so I bought a Bosch replacement:

Auto Parts Warehouse
Mass Air Flow Sensor Bosch Mass Air Flow Sensor E320|CDI Bosch
Price: $ 133.95
Qty: 1.00
Part #: W0133-1777981

The part looked the same, fit the same and seemed to be in new condition as expected. Wasn't hard to change and I was gentle. Replacement didn't change performance or remove CEL.

Then I got a Craftsman 87702 OBDII scanner, seems to work with the car as I found a few codes the first go at it.

Stored Codes:
P0069 - MAP - Barometric Pressure Correlation
P0087 - Fuel Rail System Pressure too low
P0193 - Fuel Rail Pressure Sensor High Input
P0653 - Sensor Reference Voltage B Circuit High

After clearing the codes and retest, I ended up with:
Mil DTC:
P0193 - Fuel Rail Pressure Sensor High Input
Stored Codes:
P0193 - Fuel Rail Pressure Sensor High Input
P0653 - Sensor Reference Voltage B circuit high

After checking these codes I purchased and installed:

Part:
Fuel Pressure Sensor
Desc:
Located on the fuel rail - This is a fuel pressure sensor for your Mercedes-Benz Diesel engine. This pressure sensor is located on the fuel rail.
Ships in 1-3 days - $166.87

Product Info:
Mfg Part# 0061536528
ECS Part# ES#1618729
Brand: Genuine Mercedes Benz

Home Page > ES#1618729 Fuel Pressure Sensor - Priced Each - 0061536528

This part supersedes the original part number, apparently there had been a few successions to this part, presumably due to reliability issues.

When this part showed up it was in a MBZ part box for a different part, box was opened... and this seems to have been a returned item that they sent me... so I'm not sure how to feel about whether or not I should get another one.

I installed this part on the front of the Fuel Rail, really simple, with Ignition off, I cracked a fuel line to see if the line was pressurized... it wasnt, so I worked out the old one and put the new one in... the new one has slight differences... but seemed ok, perhaps I felt it was a tiny tiny bit looser in the threads than the original, but it did fit, threaded in and does not leak fuel.

Once I started the engine, I cleared all codes to get rid of CEL... and the car ran as it used to, torquey and strong... for about five-ten minutes... I gave it some throttle and the power was definitely back... no more limp mode, got the tach over 3000 and all seemed well. Then I came to a stop light and the sputter (slight miss, hiccup, whatever) happened again at idle.

Even though CEL didn't come on, with my tester plugged in for the test drive, I erased code again, and the car did well again, and then fell back into it Limp Mode a short time after. Today I stalled at a light, and the car seems to go in and out of Limp Mode without pattern. Now CEL is back.

The only code now remains:
P0193 - Fuel Rail Pressure Sensor High Input

I think my next move is the rear pressure sensor, fuel filter, and perhaps fuel pump...

Q1) I can't find the rear sensor anywhere online easily, if anyone can point me to a link to find the rear fuel pressure sensor or P/N for the item that would be great.

Q2) What the heck could be going on?

Q3) Could something else have caused my new sensor to go bad after a few minutes of driving, since it was great the first 5 or 10 minutes of firm driving? Voltage/Short/etc in the electrical system... or...

Q4) Is the problem likely not the sensor or related electrical, but triggering this code? I hear the fuel pump may be related.

The symptoms of this issue aside from sputtering and stalling at idle, includes slight surging or surges, choppy response, wierd slow downs when rolled off throttle, etc.

I see three recall events on this car, but none appear to be related to this...but I could be wrong... I don't know if these have been done I'm not the original owner.

Any help greatly appreciated!
 
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#2 ·
What looks like sensor on the back of the fuel rail is actually electric valve part # A648 070 00 46 (PRESSURE CONTROL VALVE). The sensor on the front of the fuel rail is the one that tells the ECU what the pressure is and is part # A 004 153 67 28. Your fuel filter may needs to be replaced, but I doubt it that has anything to do w/High pressure code, it will give you low pressure if it is plugged.
 
#3 ·
I think I had the problem go away after wiggling some wires, and putting the old pressure sensor back in, it went away and drove normal for 3 days and then it came back. The codes I keep getting are high pressure, and high voltage ref circuit B. Does anyone know how to troubleshoot P0653 - Sensor Reference Voltage B circuit high?

I found an article for a VW, where you go to the ECU and disconnect circuit B and try a few things... continuity tests, et al, but I was wondering if there is anything on the w211 cdi specifically.

Also stupid question, where is the ECU, in the trunk next to NAV DVD player? I have only peeked behind the inner trunk carpeting and not fully removed to see whats back there.

Any help appreciated.
 
#5 ·
I do not see codes P0193 or P0653 In my fault code table I have, but if you using generic code reader instead if SDS it may give different code #. There is no much info on code group P0600 it only says that CAN signal is faulty.
 

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#7 ·
I'll investigate and post back my learnings. Thanks for the PICs, that's awesome. Is that blue thing a performance chip? And how to you get that cover of the ECU wiring harness off, I messed with it for a minute but didn't want to start prying at it to much... it should be simple. Thanks!
 
#9 ·
I have been studying up on EGR delete, but the threads I find are guys who make their own, soldering and resistors & potting and such... Can I buy a blue box like that online somewhere and wire in the 4 wires? All the EGR delete kits I find are for trucks not CDI's, got a resource?
 
#11 · (Edited)
Opened Fuse Box, Removed ECU, Easy. Weird brownish orange stuff on pins.

See pictures.

Unlocked fuse box, removed cover...
Found pull out tabs beneath the Wire Harness Connectors...one pulls to the front, the other pulls to the rear, when pulled wire harnesses release, simple.

The whole ECU has two spring clips you just push to the left of the car and the ECU slides up and out.

When I did this, I noticed two pins and two terminals on the plug connector that had light brownish tint, looked like arc burn, but turned out to be a liquid substance, which I find very strange. Anyone know what this stuff could be?

I wiped off the pins, used some No-a-lox anti corrosion electrical compound on the pins and replaced connectors.

I also removed my rail to injector little fuel lines to expose the wire tray and inspected wires for burns/melts/knicks and did not find any, however I did not remove the bundling tape for the wires, I just separated the bundles and tried to follow the Fual Rail Sensor wires back. Didn't see any, wiggled the wires and replaced all.

Started the car, it ran fine and limp mode was gone again, momentarily. Then I still got high pressure fuel rail code, and circuit B high voltage, but I also got another one, glow plug #1 Something... didnt write the code down, and erased codes via code reader. Ran again, and only got fuel rail and B high V, which are the most common. I did get this glow plug code twice today though.

Intermittenly after an erase things are good for a little bit, but then something happens at idle, a sputter, then CEL goes on, or it doesn't and then the car stumbles at idle... even stalling occaisionally.

This is a complicated problem... any additional ideas?

I have two, no three... wait for my replacement Fuel Rail pressure sensor, install and check.... otherwise, I'm starting to think it's the ECU, and I should have that tested.... Thirdly, I'm thinking about finally going to a MBZ dealer and paying out the nose, just to have them figure it out.
 

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#12 ·
Update...Problem Solved - Quantity Control Valve, O2 Sensor, Glowplug

Went to the dealer over the codes mentioned above.

After paying for the diagnostics... 1 hour was about $175... additional hours, if required, could be charged at that rate...

-They found that the Quantity Control Valve tested bad. It showed erratic behavior on a chart, like a messy heartbeat, and I was told it was supposed to be flat. So they replaced it. This valve is located at the top of the High Pressure Fuel Pump. The part was charged at about $285 and the labor brought it to ~$657

-They also replaced glowplug #1 $40-plus labor

-Then they said it fixed the high pressure sensor code and eliminated the limp mode, but the car was still not running with as much power, they said they kept looking and found that the O2 sensor was reading high, it was 1200 something, and spec was 383-ish if memory serves. They ordered it, kept my car for several days, replaced the O2 sensor and said it fixed it. They charged me about $270 for the part, "but I won't charge labor for it" - The part price seemed pretty inflated though.

I also had them do a ball joint that was described to be bad, for a bit over $300.

Also had them clear the SOS teleaid code. Two MBZ dealers, this was one of them, told me when I asked, that they could not clear the code. And argued with me when I said they could and that they need to see this thread - "SOS Tele Aid inoperative" message - MBWorld.org Forums. When they checked the DTB P-B-82.95/636 OCT08, they got me a liability form and cleared it. But he charged me $50 for the effort.

SO after all, plus a new fuel injector sound insulator, mine was getting deteriorated from the heat which was about $55, it all came to ~$1500

The OBD code reader got me somewhere, but it definitely wouldn't have gotten me to the Quantity Control Valve quickly.

Does this all seem fair to the crowd? They shuttled me home and picked me up in a GLK at no cost, which I think is a nice touch.
 
#16 · (Edited)
I see the OP got his issue fixed. His issue it seems turned out not to be his rail pressure sensor. I have been curious to back probe my rail pressure sensor to get some baseline readings and thought I would post them here. Looks like my reference voltage from pins #1 which is ground, and pin #3 which is positive 5 volts, pin #2 measures 1.39-1.42 at idle and increases with snap acceleration. Not sure what the voltage to pressure(bar) conversion is however. Next I will be checking the ground connection resistance to verify it is low ohm. Thought this may be a good place to deposit some information on my functioning sensor to possibly help others.

I also noticed that before starting the vehicle and with the in-tank fuel pump working the voltage between pin #1 and pin #2 measures .521VDC This may represent an easy way to get a quick generic check on the fuel pressure developed from the in-tank fuel pump and applied all the way to the rail using a good quality DVM.
 
#20 ·
I did verify that our sensor was one of them listed in this particular post. According to that information it should read 1800 Bar at 4.5VDC. I believe the sensor outputs .5VDC at O bar. That gives us .0022VDC per Bar so my 1.39VDC at idle corresponds to 404 Bar(5,946psi), and 2.0 VDC at 68MPH corresponds to 681 Bar(10,022psi). Does this sound right from what you all have seen?
 
#18 ·
I ran a quick test on the car tonight in regard to the rail pressure sensor. I strung some wire from the sensor plugin to the car interior and monitored rail pressure output voltage while driving on a DVM. Firstly I noticed that the rail pressure sensor voltage goes to about 4VDC during hard acceleration. Cruising at 68 MPH on the highway the voltage stayed close to the 2.0 VDC mark. It fluctuates a little bit depending on road surfaces, slight grade due to overpass etc. All in all my current sensor seems to change with driver demand which is exactly what I would expect to see it do. Still unsure if our sensor is 1600 bar(23,520psi) or 1800 bar(26,460psi). Once I know that I may be able to figure what rail pressures those voltages correspond to. Interesting none the less.
 
#21 · (Edited)
Lefantom,

Looking back at the photos you sent me when you got your MBII scanner I see that your idle pressure was 415.3Bar. Accoring to voltage output on my rail pressure sensor mine is at 404 Bar so that verifies my voltage per bar calculation above is on track. I also found another link from Bosch about the sensors and it also shows the .5VDC-4.5VDC range for the 1800Bar sensor:

http://www.sensorzine.com/wp-conten...ressure-sensor-1800-bar-datasheet-2560716.jpg

http://www.sensorzine.com/wp-conten...e-sensor-1800-bar-datasheet-page3-2560716.jpg

http://www.sensorzine.com/wp-conten...e-sensor-1800-bar-datasheet-page2-2560716.jpg
 
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