Low pressure exhaust sensor faulty on passat 57

Common causes of the P0420 code

• Damaged muffler or leaks in the muffler.
• Damaged exhaust manifold or leaks in the exhaust manifold.
• Damaged exhaust pipe or exhaust pipe leaks.
• A misfire in the engine.
• Oil contamination in catalytic converter.
• Faulty catalytic converter (most common).
• Faulty engine coolant temperature sensor.
• Faulty front oxygen sensor.
• Faulty rear oxygen sensor.
• Damaged oxygen sensor wiring.
• Oxygen sensor wiring that is not properly connected.
• Damaged oxygen sensor connectors
• A leaking fuel injector.
• High fuel pressure.
• Use of the wrong kind of fuel (using leaded fuel instead of unleaded fuel)

excessive fuel pressure
bad injector s
bad injector seals ,
faulty heated oxygen sensor in exhaust manifold
low tyre pressure
dragging brakes
hand brake partially on
failed cat converter blocking exhaust
dirty air cleaner
faulty Maf/vaf sensor
Faulty ambient temp senor
faulty Baro sensor
Bad driving habits
high speed driving
over drive not engaging
over loading
The list is virtually endless
However if you had a fault code reading then you can eliminate most and get to the reason that you are seeking

I don't know much about the diesel particulate filter system yet other than what I have read.

All the articles on the subject I have seen so far indicate the trigger for starting the automatic DPF cleaning cycle is excessive exhaust back-pressure. When the pressure sensor in the exhaust detects excessive pressure the engine management values are changed to make the exhaust very hot and a special solvent from an on-board reservoir is forced into the system and the cleaning process of the DPF is underway.

The articles suggest topping up the reservoir of special solvent is a routine service item. Anecdotal evidence suggest neither the cleaning process or the topping up are automatic or routine but rather another way for dealers to rip-off customers.

When the cleaning process no longer restores minimal back-pressure the DPF must then be replaced at what anecdotal evidence is a very high cost.
I could be wrong but I suspect before the engine management system recognises excessive back-pressure to be a problem and record it as a fault it would have to record a certain number of instances in a certain time-frame and if that criteria isn't being met there will be no faults stored.
Certainly this is a case for an obd recorder to be fitted to your car to record the live data which can be analysed by the dealer later.

I speculate the pressure sensor, wiring or connectors might be faulty or inaccurate or you really do have a back-pressure problem, either because the DPF they fitted is faulty or of poor quality, the work is of poor quality or because there is something wrong with the rest of the exhaust system.

Personally, because I have experienced back-pressure problems increasing during a journey being caused by exhaust silencer boxes I would start by removing everything rear of the DPF and give each part a shake and compare the weight with a new one of the same type.
Just my opinion you understand.

I would need to refer to a wiring diagram and an overview of the engine management system to form an opinion whether the exterior temperature indicator is a coincidence or is linked.

Good luck!

Reasons for increase in fuel consumption include a fault in the fuel pressure in the manifold, cpu keeping the fuel rich for too lomg Water/ air tem sensors. Brake drag -Brakes staying on slightly.tyre pressure too low blocked exhaust system cat converter clooapsed and blocking exhaust pipe. faulty oxygen sensor. driving in too low a gear for too loong Faulty auto tranny not changing at the right time. Considerwhen the consumption went up and try to remember if something happened that at the time seemed incindental as this may help pinpoint the fault

P0029 - Exhaust Valve Control Solenoid Circuit Range/Performance Bank 2
Causes:
- Dirty engine oil
- Low engine oil level
- Exhaust valve control solenoid circuit open or shorted
- Exhaust valve control solenoid circuit poor electrical connection
- Faulty exhaust valve control solenoid

Solutions:
- Change oil
- Replace exhaust valve control solenoid

P0047 - Turbocharger/Supercharger Boost Control A Circuit Low
This vehicle is not equipped with a turbocharger or supercharger if it is a 1994.

P0137 - o2 Sensor Circuit Low Voltage Bank 1 Sensor 2
Causes:
- Sensor circuit harness or connectors is open or shorted
- Rear heated oxygen sensor Bank 1 may be faulty
- Fuel pressure may be faulty
- Fuel injector may be faulty
- Intake air leaks

Solution:
Replacing the O2 Sensor 2 usually takes care of the problem.

P0107 - Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
Causes:
- Damage harness or connectors
- MAP sensor circuit is open or shorted
- MAP sensor
- Damaged PCM or ECM

Solutions:
- If damage, repair MAP sensor harness or connector
- Replace MAP sensor
- Replace PCM or ECM

The DPF is designed to be self-cleaning to a certain extent if the engine is run for a good length of time the deposits should burn off. I would kick up a fuss with Audi about the warranty, ask them to show its exclusion. Unless the DPF has become physically damaged by something you have done then they need to have it fixed as it is a result of the deficiency in their design. This is not like some damaged tyre, open to abuse by the driver, the DPF is integral to the vehicle operation and through no commission on your part it is not functioning as it should.

Exhaust pressure sensor a possibility if it has a DPF (diesel particulate filter). Has it had its fuel pump recall, the oil pressure light could be just the constant cranking and running the battery low.

no the manifold psi is getting to high

Hi, I have a 2001 polo 1.4 mpi it lackes power when you hit a hill it just dies, It has had new cat, fuel filter, fuel pump and throttle body, but is still the same it just dose not want to give me full rev's?