2009 ML 320 Bluetec persistent fault code 14A600, lack of powerHi, anybody encounter this problem? fault code 14A600 - positive control deviation of exhaust gas recirculation control is too high. The engine has excellent idling, start quickly and no smoke at tail pipe but unable to rev over 3000 rpm. No other fault code appearing. I already replaced the two orange seal at turbo inlet and PCV inlet on the clean air Y-pipe then smoke test the entire inlet from engine air filter to the intercooler outlet but no leak was detected in and outlet pipe of the turbo. Removed and cleaned EGR valve not much soot found, inspected the internal corrugated EGR pipe, no deformation or obstructions found, remove the EGR pipe from EGR cooler outlet and found it was clogged, removed the harden soot from the pipe, blow compressed air to the EGR cooler and pipe. I thought this was the only problem but when I test drive the SUV the fault code had come back again. I Checked the continuity of all the wires from the harness, those wires coming from MAF sensor, throttle intake temperature sensor, EGR inlet temp sensor and oil temp sensor all signal wires have continuities. I also I checked the opening and closing of the EGR valve by supplying 12 volts power to the EGR terminals and it opens and closes smoothly. I believed no issue with wiring harness. I appreciate your comments, thank you.

 

Did you delete the code & then checked for codes again?

 

Yes, I always do that every time I deleted the code I have to check it again to ensure it was deleted completely. The fault code will not come back quickly it take 1-2 driving cycle before it appear again, On a flat level highway, speed can reach over 130 km/hr (caution to speed camera) but uphill is slow and a bit struggling.

 

Maybe you should consider replacing the EGR positioner. It's expensive.

 

Thanks Maj. Dundee, you are right it is very expensive so before I replaced the EGR valve, I would like to try first the least expensive one by removing and performing a function check of the exhaust gas back pressure sensor (this is the sensor near EGR valve) because if this sensor is not sensing pressure at the turbo the EGR will not open. I did a bench function check of the EGR valve by supplying 12V and it is opening and closing several times without fail. I also take resistance reading on the signal wire then manually actuating the pintel to close and open and I can see that the resistance is varying from low to high resistance as I fully opened the valve the resistance goes higher too. So I believed nothing wrong with the EGR. Worst come to worse, I am also thinking of removing and dismantling the EGR motor and see any defective parts and see what I can do to fix before buying new one. I am just fed up buying too expensive parts.

 

Maj Dundee, have you experience any problem with the Turbo actuator (the Black plastic box mounted on the front side of turbo charger) as if this is defective, it can limit the amount of turbo output/discharge that can limit the rpm too. I watched some you of tube videos that they found out the fusible link inside is broken. So by just soldering some fusible replacement wire they can be able to fix the problem of Limp mode and lack of engine power. Not sure if this is connected to my problem fault code 14A600. I might do this simple check, it is easy and can be done quickly to check if the fusible link is broken.

 

I do not own one of these CDI vehicles which are money pits. I have no idea what the Black plastic box mounted on the front side of turbo charger is.

You must check all wiring harnesses connected to the EGR. Other than that, I have no other suggestions.

 

OUOTE: rrvtechcon; Yes, I agree but before replacing EGR valve I would like to test also wiring and functionality of EGR temp sensor in addition to exhaust back pressure sensor as this controls the EGR valve.

 

[QUOTE=Maj. Dundee;8292778]Maybe you should consider replacing the EGR positioner. It's expensive.[/QUOTE

{QUOTE=rrvtechcon] Checked wires going to Exhaust Back Pressure sensor and I got good signal ground, I also got the 5 volts ref voltage confirmed OK but the signal line from EBP sensor to ECM is only .70 volts at idle and only 1. 6 volts @ 4000 rpm. This is too low, I should be getting at least 3-4 Volts same as of the MAP & MAF sensors signal voltages. I am ordering new EBP sensor. By the way, when I cleaned the EBP sensor with brake cleaner and blow compressed air and put it back, I was able to rev over 3500 rpm but after 30 sec. check engine light came back again. Will see after I replaced the sensor.

 

Now you got a different code # or is it a typo?

 

Correction, the same fault code 14A600.

 

The test procedure is very confusing and to do it requires 3-4 sockets. It is not worth it.

 

Thanks Maj Dundee, I will try that procedure but while waiting for the EBP sensor, I unplug the EBP sensor then start the engine and drive. Idle is good and everything look normal I can rev even as high as 4500 rpm and I was able to do regeneration of DPF while accelerating, The fault code 11A600 has disappeared but it was replaced later by 1 code 118900 component B60 (Exhaust back pressure sensor) has a plausibility. My DPF differential pressure sensor reading after regeneration at idle is 3 hpa and 55 hpa (0.79 psi) at 3500 rpm which is normal for a clean DPF.

 

Maj Dundee, there are 4 male pins from the EGR valve while the wire harness connector has 4 females but only 3 wires one is empty not sure which one is (Y27/9x1) 3 and 2 (Y27/9x1) I guess one of the wires is Red & Brown? please confirm.

 

Here is the diagram (scroll down to view) and legend.

 

[QUOTE=rrvtechcon] I was able to take voltage reading as per the diagram /instructions and it was 11.5 V so there's no problem with the supply voltage to EGR (Y27/9). I also took continuity test of each wires from EGR (Y27/9) to inlet port shut off motor(M55) and to charge pressure positioner (Y77/1) (turbo side) all of the 2 wires were OK. The only wire I was not able to check is the grey-yellow signal wire from CDI unit terminal # 71 to the EGR terminal 1. I already found the location of the CDI unit but it was too tight to remove the wire harness connector, I am a little bit worry of damaging if I force it. Do you know if there is a lock clip or mechanism to secure it from the CDI terminals? My intention is to take continuity test of this wire and other wires from CDI to M55 and Y77/1. Otherwise, I will just take voltage reading key on to the signal wire and ground if 5 volts is there then that signal wire from the CDI unit is OK. I suspect that the EGR do not open when needed because the CDI is not giving signal to open the EGR valve. Appreciate any comments/suggestions?

 

Hi, I'm having the same fault code. Changed egr but still the same, did you ever resolve the problem?

 

Unfortunately, I was too fed up, so I surrendered and sold it without resolving the problem. The buyer told me he will just delete the EGR and have his friend do the ECU tune up to remove the EGR from the system. But before I sold it I was able to ask a good Mercedes Benz indy shop and gave me a quotation for checking all the sensors & wiring associated with the EGR like the speed control sensors from the 4 wheels, back pressure, inlet air temp sensors, MAF & MAP sensors too but the labor hour cost is high to proceed that I just decided to sell it and ordered a 2021 Tesla model 3. This Mercedes Bluetec SUV is very problematic and also a money pit when it reaches over 100K km mileage they have a poorly designed emission system component compared to other vehicles. I hate this car brand and will never buy a Mercedes car again. I hope this information helps you.