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Posted on Apr 21, 2009

My Audi A3 2.0 tdi limp mode/turbo overboost

My Audi A3 2.0 tdi BKD engine code, has recently been going into limp mode, fault registered as turbo over boost.

I had the turbo changed at the weekend and for a day the car worked fine. Then limp mode again.

Sometimes I can hear an air leak from below the drivers seat on the right hand side of the car, outside the car obviously. Is this connected to why my turbo keeps over boosting and the car entering limp mode?

Would changing the N75 valve help anything?

  • Anonymous Apr 21, 2009

    i had same problem, it was the unit injectors which had failed

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  • Posted on Sep 14, 2009
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I also have done a diagnostic test and it states a turbo overboost condition and it drives fine locally but loses power on the motorway and struggles to reach 80mph? any suggestions please email me at [email protected]

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  • Posted on Jul 22, 2013
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I have the same problems it is chowing my diesel aswell

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  • Posted on Aug 02, 2012
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I have the exact same problem. Did you ever manage to resolvet this?

  • Anonymous Dec 06, 2016

    Heya,



    Just for anyone suffering in the future i cleaned out the AGR system and N75 module to no avail. In the end someone said it might be a sticky turbo if its not been run on motorway 'stretched its legs' so to speak. So i started driving everywhere in a lower gear to get the turbo spooling and working harder. Someone described it as 'drive it like you stole' . I worked the turbo like this for a few weeks, making sure that i let the turbo run down before switching off the engine and it hasn't gone into limp home mode since...... basically think it was clogged up with years of town driving.

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  • Posted on Jul 16, 2012
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Could be the air mass sensor or related sensors. i had this same problem on a 1.4 polo tdi i owned 2 yrs ago. tried all sorts of things and recommendations but turned out to be the air mass meter/sensor.
lee

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AUDI A3 OVERBOOST 20. TDI 04 SAFE MODE ISSUE

Code P0234 Check N75 boost control solenoid and all vacuum hoses to and from N75.

If performance returns after brief ignition key cycling, Off /On.....check for vacuum to turbo dump valve canister.

If performance is always low, check turbo vanes for sticking or 'snow screen' in snorkel to air filer is not restricted..
tip

How to fix "limp mode" on Audi TDI

If the car goes in "limp mode"!!!
After scan the EDC-15P engine control unit with a VAG or KTS -BOSCH diagnosis tool you will find this: Fault code: P1557-Turbo Boost pressure control exceeded
1. Engine stopped and ignition switch off. Check all pneumatic connections and hoses between turbocharger actuator = pressure unit for boost-pressure control, boost-pressure control solenoid valve, vacuum reservoir, EGR control solenoid valve, intake-manifold flap solenoid valve, EGR valve with throttle - part of intake manifold. Also the vacuum connection between tandem pump and brake booster. If you find something wrong replace parts. If not go to step 2.
2. Extract the hose of the turbocharger actuator = pressure unit for boost-pressure control part of turbocharger. Instead of the original hose you must place another 1 meter long hose with the same inside diameter, and then you check to inspire yourself the air from the other one extremity of this hose. The mechanical connecting rod of the turbocharger actuator must have a smooth and whole motion. If you can do that with your mouth, then you must replace the boost-pressure control solenoid valve. If you can not reach this with your mouth, then you go to step 3.
3. This is the most difficult work. The problem is that the soot particles deposits inside the turbocharger plugging the variable nozzle geometry mechanism = adjustable vanes of the turbine. If the turbocharger actuator is not able to adjust the turbine vanes the charge air pressure increase too much and ECU (engine control unit) go in "limp mode" = engine protection software. As a result the "limp mode" engine still running until you turn the engine off (ignition switch off) and back on when the "limp mode" is deactivated, but the fault still remain in ECU memory!
4. You must be able to extract the turbo from the engine and then to disassemble the turbocharger, clean inside adjustable vanes mechanism and refit all.
on Dec 04, 2009 • Audi A4 Cars & Trucks
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I have an Audi A4 1.9 TDI. Motor code: AWX. 2003 Prb: When accelerate, the turbo worked properly but after 120 km, the turbo cut off and when i switch off and on the engine, the turbo restart to work. Can...

In your case the turbocharger is responsible for engine losing power.
The car goes in "limp home" mode!!!
After scan the EDC-15P engine control unit with a VAG or KTS -BOSCH diagnosis tool you will find this: Fault code: P1557-Turbo Boost pressure control exceeded
1. Engine stopped and ignition switch off. Check all pneumatic connections and hoses between turbocharger actuator = pressure unit for boost-pressure control, boost-pressure control solenoid valve, vacuum reservoir, EGR control solenoid valve, intake-manifold flap solenoid valve, EGR valve with throttle - part of intake manifold. Also the vacuum connection between tandem pump and brake booster. If you find something wrong replace parts. If not go to step 2.
2. Extract the hose of the turbocharger actuator = pressure unit for boost-pressure control part of turbocharger. Instead of the original hose you must place another 1 meter long hose with the same inside diameter, and then you check to inspire yourself the air from the other one extremity of this hose. The mechanical connecting rod of the turbocharger actuator must have a smooth and whole motion. If you can do that with your mouth, then you must replace the boost-pressure control solenoid valve. If you can not reach this with your mouth, then you go to step 3.
3. This is the most difficult work. The problem is that the soot particles deposits inside the turbocharger plugging the variable nozzle geometry mechanism = adjustable vanes of the turbine. If the turbocharger actuator is not able to adjust the turbine vanes the charge air pressure increases too much and ECU (engine control unit) goes in "limp mode" = engine protection software. As a result the "limp home" mode engine still running until you turn the engine off (ignition switch off) and back on when the "limp mode" is deactivated, but the fault still remain in ECU memory!
4. You must be able to extract the turbo from the engine and then to disassemble the turbocharger, clean inside adjustable vanes mechanism and refit all.
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Twice in the last 2 weeks the turbo on my 2.0 TDI Audi has shut down while driving. To reset it I have to stop, switch the engine off and then back on again. I took it to the dealer who tells me I need a...

In the most cases for Audi 2.0 TDI the turbocharger is responsible for engine losing power.
The car goes in "limp home" mode!!!
After scan the EDC-15P engine control unit with a VAG or KTS -BOSCH diagnosis tool you will find this: Fault code: P1557-Turbo Boost pressure control exceeded
1. Engine stopped and ignition switch off. Check all pneumatic connections and hoses between turbocharger actuator = pressure unit for boost-pressure control, boost-pressure control solenoid valve, vacuum reservoir, EGR control solenoid valve, intake-manifold flap solenoid valve, EGR valve with throttle - part of intake manifold. Also the vacuum connection between tandem pump and brake booster. If you find something wrong replace parts. If not go to step 2.
2. Extract the hose of the turbocharger actuator = pressure unit for boost-pressure control part of turbocharger. Instead of the original hose you must place another 1 meter long hose with the same inside diameter, and then you check to inspire yourself the air from the other one extremity of this hose. The mechanical connecting rod of the turbocharger actuator must have a smooth and whole motion. If you can do that with your mouth, then you must replace the boost-pressure control solenoid valve. If you can not reach this with your mouth, then you go to step 3.
3. This is the most difficult work. The problem is that the soot particles deposits inside the turbocharger plugging the variable nozzle geometry mechanism = adjustable vanes of the turbine. If the turbocharger actuator is not able to adjust the turbine vanes the charge air pressure increase too much and ECU (engine control unit) go in "limp mode" = engine protection software. As a result the "limp home" mode engine still running until you turn the engine off (ignition switch off) and back on when the "limp mode" is deactivated, but the fault still remain in ECU memory!
4. You must be able to extract the turbo from the engine and then to disassemble the turbocharger, clean inside adjustable vanes mechanism and refit all.

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Audi A6 3.0 tdi Quattro 2005, glow plug light comes on, limp mode

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Engine managment light flashes (glow plugs light)

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At 2500 - 3000 revs in top gear my golf turbo loses power

Sounds like the car is going into limp mode, and then resuming normal operation the next time you start it. This is probably due to an overboost or under boost situation. If this is the case, the car's computer can't effectively control the boost the turbo is producing, so it just "turns" the boost off. Ask the shop what the engine code was specifically, and then compare it to VW specific codes. ( google "VW OBD codes"). I'm betting the code is either P1556 (boost control negative deviation, underboost), or P1557 (boost control positive deviation, overboost). Proper diagnosis with VW specific software is half the battle. The rest is methodical troubleshooting by you or your shop so you don't replace parts that don't fix the problem. No offense intended, but it sounds like you need to bring your car to a shop that knows VW's. Sorry I'm not more helpful, but without more info, I'm just taking a guess. I've actually had this problem with my Tdi, and the fix was cleaning the intake manifold and a slight turbo actuator adjustment. But, in your case, several things could cause this which is why proper troubleshooting is important. Hope this helps.
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Overboost condition

Hello, your car is probaly a variale vane turbo fitted and all you need to do is seperate the VNT part of the turbo, give it a good clean with brake/carb cleaner get rid of the sticky oily residue which makes the vanes stick on turbo causing a overboost fault, a delearship might tell you that your car has been remapped at some time setting the boost RPM at like 14 or 1500 and it should be like 2200 I do not know the specifics on your vehicle but a good auto manual will tell you at which RPM your boost should build. I would have a diagnostic done and see if this is your problem, if so do the above and go back and see if it fixed your overboost problem. If not, you will need your ECU remapped. I hope this fixes your problem!
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Turbo over boost on audi a4 1.9 tdi sport, goes into limp mode when i reach 60mph. emp,reads error code p1557

I can help you to fix this problem. "Fault code: P1557 - Turbo Boost pressure control exceeded"
But I need some info from your engine:
- what type of engine do you have (engine code: ex.ALH, AJM, AWX, ...) or power in kW (PS)
- how many km (miles) are your car?

My e-mail adress is: [email protected]



5helpful
2answers

Audi a4 1.9tdi

Your car goes in "limp mode"!!!
If you scan the EDC-15P engine control unit with a VAG or KTS -BOSCH diagnosis tool you will find this:
"Fault code: P1557 - Turbo Boost pressure control exceeded"
You must try follows if you are able to do this:
1. Engine stopped and ignition switch off. Check all pneumatic connections and hoses between turbocharger actuator = pressure unit for boost-pressure control, boost-pressure control solenoid valve, vacuum reservoir, EGR control solenoid valve, intake-manifold flap solenoid valve, EGR valve with throttle - part of intake manifold. Also the vacuum connection between tandem pump and brake booster. If you find something wrong replace parts. If not go to step 2.
2. Extract the hose of the turbocharger actuator = pressure unit for boost-pressure control part of turbocharger. Instead of the original hose you must place another 1 meter long hose with the same inside diameter, and then you check to inspire yourself the air from the other one extremity of this hose. The mechanical connecting rod of the turbocharger actuator must have a smooth and whole motion. If you can do that with your mouth, then you must replace the boost-pressure control solenoid valve. If you can not reach this with your mouth, then you go to step 3.
3. This is the most difficult work. The problem is that the soot particles deposits inside the turbocharger plugging the variable nozzle geometry mechanism = adjustable vanes of the turbine. If the turbocharger actuator is not able to adjust the turbine vanes the charge air pressure increase too much and ECU (engine control unit) go in "limp mode" = engine protection software. As a result the "limp mode" engine still running until you turn the engine off (ignition switch off) and back on when the "limp mode" is deactivated, but the fault ("Fault code: P1557 - Turbo Boost pressure control exceeded") still remain in ECU memory !!!
4. You must be able to extract the turbo from the engine and then to disassemble the turbocharger, clean inside adjustable vanes mechanism and refit all.
It is some work to do here, but after that you will be full satisfied! NO MORE "LIMP MODE"!!!
--------------------------------------------------------------------------------------------------------------------------------------------
It is a certified solution. Last year in July I made this turbocharger cleaning on my car - 2000 Audi A4 1.9 TDI 116 HP. After 25000 km my car runs like an authentic AUDI 1.9 TDI.
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