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EGR problems: broken connector or damaged ECU?

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Dear community,

I recently had a lot of trouble with my beloved 2008 Avensis D-4D (ADT250, 1AD-FTV engine). It all started with white smoke coming out of the exhaust on a regular basis, together with an occasional P2002 DTC. The workshop I brought the car to did the following (in several sessions):
- mechanical cleaning of the DPF
- exchange of all four injectors
- exchange of the rubber hoses between DPF and differential pressure sensor
- exchange of the fifth injector
- cleaning of the EGR valve
- cleaning of some pipes between the turbocharger and the cylinder block
- temporary exchange of the differential pressure sensor
- exchange of the EGR valve

The P2002 DTC and a lot of my money went away but the white smoke persisted, so that I decided to take things into my own hands, ordered a mini-vci with the latest techstream software and started testing. I noticed several things but don't know how to continue:

1. First of all, the car sometimes throws a P0405 DTC (without the MIL being illuminated) which usually goes away at the next start.
2. When the car is idling, the EGR related values do not make sense to me: The target EGR position is always around 20% and the voltage around 70%. Shouldn't te valve be completely closed when idle?
3. When starting the car, the lambda value is close to one as it should be, with zero voltage. After driving for a few minutes, the air/fuel ratio sensor becomes active (at least I guess so) and then within twenty seconds or so lamba increases to 1.9998 and then reliably stays too high, i.e. is at least 1.3 until the ignition is turned off. Even when going back to idle, it sometimes constatly stays at 1.9998.
4. after every test drive, there is a failed egr monitor in the system (without any DTC being thrown). The problem is always with "EGR FLOW #2", the min value is always 1996.062mm and the test value always far away from that)
5. When turning on the ignition without starting the car, a clicking noise is coming out of the diesel injector driver ECU as if a relay is constantly opening/closing. The rate is approximately two clicks every second with the time between clicks being very regular.
6. I also noticed that my MAF values are probably not good, here are the values when idling (in pairs of rpm and maf in gm/sec): 800, 8.17, 1300, 13, 1500, 16, 2100, 24, 2540, 33, 2800, 41, 3150, 50.

I think that the reason for the high lambda value is a wrongly operated EGR valve, which constantly lets too much air into the system. Can this be correct? Also, could too much air also cause white smoke coming out of the exhaust? If so, the strange thing is that I can sometimes drive with a constant lambda value of 1.9998 without any white smoke appearing.

Regarding the EGR valve itself: Currently I have a brand new one installed but also replaced it with my old one and a borrowed one, always with the same result as above (EGR FLOW #2 fails, min value always 199.062mm, test value far away). The problem therefore has to come from the ECU or the connection (broken cable?). I metered the connector and it supplies constant 5 Volts as it should, which leaves the other three pins or the ECU as the culprit. Is this reasoning correct? Does anybody have the relevant electrical wiring diagrams so that I know which are the relevant pins on the ECU to continue metering? Is there some fuse or relay which can cause the problems I'm having? Has the diesel injector driver ECU any influence on the EGR valve?

Here is some techstream data:

idling just after starting (screenshots 1 and 2, note the strange EGR related values and that the lambda value is ok)


after some minutes of driving (screenshots 3 and 4, lambda value has gone through the roof)

after some more minutes have passed (screenshots 7 and 8, lambda value is somewhat lower around 1.3, egr values are still strange)

feeze frame data of P0405, thrown just after turning the ignition on, without the engine running (screenshots 11, 12, 13)



failed EGR monitor, which is stored after every drive (screenshot 14)

I would be very thankful for any help!



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