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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3740
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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I have a 04 ML350 that is setting a P022 code. The

Customer Question

Hello, I am Richard, I have a 04 ML350 that is setting a P022 code. The accelerator pedal sensor has been replace 2 times and the throttle body along with the TPS sensor has been replace twice. The car still goes into a limp mode and it seems to happen after hitting a mild nothing serious bump. The shop where it is is unable to do any more diagnosis due to not having the right equipment. They are suggesting a wiring or computer problem. Any suggestions
Submitted: 1 year ago.
Category: Mercedes
Expert:  Lou P. master tech replied 1 year ago.
Hello my name is ***** ***** i will do my best to help you , i strive for EXCELLENT service and nothing less. Hello Richard , can you give me the full fault code yours is missing a digit. I'm sure I can help you with this. I also have another customer with a similar issue. Lou
Customer: replied 1 year ago.
Sorry, I left off an additional 2. So the code is P0222
Expert:  Lou P. master tech replied 1 year ago.
Ok that was what I thought. So the issue only happens when hitting bumps ?
Customer: replied 1 year ago.
It didn't start out that way, but it seems like the last couple times it has happened it was when we hit a bump. I just drove it home from the shop (less than 1 mile) and it has a delay when starting to accelerate for about 3 seconds. Then it seems to accelerate fine. The mechanic said it went into complete limp mode yesterday until he put it in neutral / mashed the pedal to the floor, turned it off and back on then was able to get it back to the shop in the delay accelerator mode..
Expert:  Lou P. master tech replied 1 year ago.
Ok. Let me review a few things and get back to you with a plan.
Customer: replied 1 year ago.
Ok, thank you.
Expert:  Lou P. master tech replied 1 year ago.
No problem. So do you have a scan tool to check the codes ?
Customer: replied 1 year ago.
Unfortunately no I do not.
Expert:  Lou P. master tech replied 1 year ago.
Ok. That is going to be a issue. As without clearing the codes we will not know if they will come back. I'll see if we can find a way around this.
Customer: replied 1 year ago.
I will see if I can rent one somewhere. Is there a specific model you suggest that I could get at a store
Expert:  Lou P. master tech replied 1 year ago.
Just a generic code scanner that can read and erase. Nothing special
Expert:  Lou P. master tech replied 1 year ago.
Ok so if the code has set when the engine is running the car throttle will not respond. So what I want you to do just to check is follow the wires into the fuse box. Remove the fuse box cover and also the bigger cover that covers the whole box , it will be 6 torx screws. T20 I believe. And find a square connector that had the same color wires as the accelerator sensor. There is a connection that is between the ECM and the accelerator sensor and it's located inside the fuse box. Not to be confused with the literal term of fuse box , shuffle through all the wiring and make sure no wires are chewed up from mice or anything. I have another customer with the same exact issue as we speak so I'm trying to get you both fixed up. The possibilities are sensor , wiring , connector , or ECM. Since hitting a bump causes this issue it will be a chewed wire or poor connection. You should be able to wiggle the wiring and get the fault to happen. That's why I want the scanner. To erase the code so you know then the fault happens. If the light is always on it will be hard to tell if the fault occurred. Does all this make sense?
Expert:  Lou P. master tech replied 1 year ago.
http://www.mediafire.com/view/s814aiyjfbjbagu
Copy and paste that. It is a picture of the connector face. Hope this information helps
Customer: replied 1 year ago.
which fuse block, the one on the passenger side inside or the one under the hood on the drivers side. neither really look like the diagram you sent
Expert:  Lou P. master tech replied 1 year ago.
Ok sorry , the engine bay fuse box. Remove the smaller cover that has two tabs. Then use a torx screwdriver to remove the over 6 screws to remove the bigger lid. Inside you will find a overwhelming amount of wires. Look for a connector that looks like the picture i sent and will have the same color wires as the accelerator sensor.
Customer: replied 1 year ago.
i have removed that, i am not sure were the pedal sensor is located to find the wire color. I have taken the cover under the dash down but I only see like a pedal stop at the bottom on the floor. only a cable coming off the pedal itself
Customer: replied 1 year ago.
ok. i believe i found a couple sensors under the hood by the cable coming off the pedal. one has 4 wires and 1 has 2 wires. which one is the pedal sensor
Customer: replied 1 year ago.
also, is this connector on the ecm, I don't see another connector that necessarily looks like the picture that you sent with the same color wires.
Expert:  Lou P. master tech replied 1 year ago.
Ok the sensor is the one up high that the cable goes to. And the connector is inside the fuse box area the picture I sent is the best I can give you. Your gonna have to find the sensor and check the wires and the fuse box area for the matching wires
Customer: replied 1 year ago.
If the sensor has 5 wires coming out of the connector, I did find the sensor. I think I found the wires in the fuse box but it goes to a connector that has roughly 30 pins (15 down each side). The wire colors I am seeing are blue, brown, white, gray, and green. If these are correct, I didn't see anything obvious on where there were any open insulation. The wire loom / tape that they leave the sensor with into the fuse box is intact and does not have any cuts or anything in it. I didn't see any in the wires themselves at either end on first glance, but I am out of day light now, and unfortunately I don't have a garage I can really work in right now as I have other crap in there. I was using a flood light to look at the wires at this point but would like to verify that you think I have the correct ones and then look at them in the day light. I was not able to get a code reader yet, the local store up the street were out of stock, I will get one when I come home from work tomorrow. If you are available tomorrow to go further I will take off a half day (I have to go in for the morning, I have a meeting to attend). Let me know if this is ok, and what the next step is if these wires are correct. It sounds like you want me to erase the codes, then start the car and giggle the wires to see if it resets the codes or something, is that correct? Thank you very much for your time.
Expert:  Lou P. master tech replied 1 year ago.

You are correct with my approach to wiggling the wires. Also the connector will have way more than just the wires we are looking for. That's why we need to match up the wires. Every wire is specific so you cannot mix up wires. And don't take a day off on my account I can't promise I can be there as much as I have be. And don't want you to put your job on hold.

Customer: replied 1 year ago.
No worries, I still want to look at this in the day light and won't really have much time for that beyond tomorrow so we will see how that works out. I will do a lot more verifying of the wires tomorrow and jiggle them as you have suggested and see what I get. I will let you know what I find and then when you have a chance you can let me know what I should do based on that when you get a chance. Thanks very much
Expert:  Lou P. master tech replied 1 year ago.

Ok no problem. I'll do what I can. Have a good night. Lou

Expert:  Lou P. master tech replied 1 year ago.

The wires are the following. Blue , pink,white,green, and grey

Customer: replied 1 year ago.
Hello Lou. Sorry I couldn't get back to you yesterday. I did get a code reader and I tested the vehicle when I got it home. It has two codes. one is P0121 and the other is the P0222. I cleared out the codes and have not been able to get them to come back on. The one thing I am not 100% sure of is if I can do have the car running while testing the wires. I tried it both ways but didn't get any response either way. I was able to trace the wires all the way from the pedal sensor to the ecm. I did a resistance (ohms) test on them and all the readings from the sensor connector to the next large connector were .0 or .1. From the large connector to the ECM connector were pretty much the same. From the ECM all the way back to the pedal senor connector were at worse .6. So they were all under 1 which most the time means they are ok from my knowledge. The one thing I found when I was taking the sensor connector off was that someone broke one of the clips that holds that connector to the sensor. I really tried to move that connection at the sensor both with the engine running with the OBD reader and without it connected and was not able to get it to reset a code. I am not sure if that is enough to set it off and I was just not able to have it replicate or if it really doesn't matter. That is where I am at this point. Look forward to hearing what you think at this point. Thanks very much
Expert:  Lou P. master tech replied 1 year ago.
You're doing everything right it looks like the car is not cooperating with you LOL, what I want to see this freeze-frame just want to code return almost all standard show up freeze-frame data
Customer: replied 1 year ago.
I can drive the car around the neighborhood to see if I can get the code to come back if you need other information from the codes again. Let me know if that should be my next step
Expert:  Lou P. master tech replied 1 year ago.
Well yes. As soon as the code comes back read the freeze frame and upload all the info. That will tell me the temperature speed and throttle angle the issue happened at.
Customer: replied 1 year ago.
Just an update, I ran the car for about 40 minutes around the neighborhood this afternoon, it didn't recreate the fault at this point. I will keep trying and hopefully have something in the next day or so. I am pretty busy this weekend but will keep trying.
Expert:  Lou P. master tech replied 1 year ago.
Ok. No hurry on my end. We are not timed. I'm ready to help whenever. Lou
Customer: replied 1 year ago.
thank you, ***** ***** trying to get it to recreate on roads that if it does go into limp mode that i can get off the road easy enough and not have to worry about getting into an accident. I am not sure that will make it happen but I will continue to work on it.
Expert:  Lou P. master tech replied 1 year ago.
That is the best good job. Finding the scenario to recreate it is something most technicians don't even think about !

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