Hello to you all. I have got a persistent problem of getting the P200200 when the engine is cold after start.

My car - Skoda Octavia 1.6TDI CXXB. Mileage 145k miles.

It looks like it appears only after start and then if I clean it it does not reappear again. It triggers the EML light after some time or after the second start.

What has been done:

Low pressure EGR cooler assembly (cooler and valve) replaced by myself to a new MAHLE one.

DPF filter was taken from the car in the garage and professionally cleaned at a dedicated equipment off-car.

The high-pressure EGR valve was cleaned by me.

The throttle body was cleaned by me as well.

I have checked the fuel injector time deviation and it is within the limit as well.

What is left? Glow plugs?

Maybe someone has already encountered something like this? I don't know where else to dig.

P.S. I also use VCDS to diagnose my car, not just the carscanner. But it doesn't help. Thank you

Is the egr valve working properly. Might be worth checking its holding vacuum. Had one fail on a Seat 1.9tdi. Vacuum diaphram was leaking. Another thing to check is the DPF/exhaust pressure sensor. Had a quick google and its sensor G450. No idea where it may be on the MK3 but according to google looks like this.

Alasdair

Thank you very much for your reply.

I have checked the sensor. In fact I tried replacing them and tried few others. No difference.

Concerning the EGR valve. What valve are you referring to? Low pressure EGR or high pressure EGR? Could you please be more specific on the vacuum problem?

Mine was a 1.9tdi engine and only had one EGR the vaccum actuator diaphram had failed so egr and kept getting insufficient flow codes. Looks like this

Sorry didnt realise that the newer engines (mine were MK2) have two and electrical rather than vacuum operated. Maybe a wiring fault to egr somewhere or a slight exhaust leak before DPF. Read when you change G450 theres a procedure with VCDS to adapt it to car. If its not done it can keep throwing up codes.

Alasdair

Thank you, I have performed the adaptation procedure, but it does not help. Some leak could be a reason. I need to check for leaks, though I think it would have introduced itself by other faults.

20 hours ago, karp said:

DPF filter was taken from the car in the garage and professionally cleaned at a dedicated equipment off-car.

Waste of time and money. Cleaning will only remove the carbon that should be burned during the regen process. Main problem with these damned things is they clog up with ash that is effectively embedded in the ceramic core and no amount of pressure cleaning will get it out without damage to the core. Like turbos, they have a service life of around 140 - 150 thousand miles so yours at 145,000 odd is probably due for replacement.

I believe on certain engines the upstream o2 sensor works with ecu and dpf. If its sending false readings it can confuse ecu etc and have read on rare occasion it can trigger same code. I would check its working properly or change it as there not that expensive unlike a new dpf.

Alasdair

Thank you. I have also found that with the maf unplugged the whole egr system does not work and the P200200 code does not appear. Also, I have measured the MAF flow with EGR systems on and it looks like it should be lower with the Low pressure EGR in operation, hence probably the low pressure EGR radiator is clogged again (