Ongoing electrical issues, any thoughts please

[Streakie]

This will not be brief.
This all seemed to start with lack of aircon, and poor running issues
Ok since getting the 2007 T28 1.9tdi I am sure the aircon did once work, but does not now, I am now thinking it never did
and the van would start badly, ie cranks over for ages before starting in the morning, unless its bitterly cold, then it goes first time.
So I replaced, Coolant Temp sensor, checked glow plugs(tested ok) replaced fuel filter, mass airflow sensor, air filter, and battery.
I put p with it for ages, and jst got on with life,
So running issues started building up, lack of power, smoking on acceleration, sluggish throttle,
cleaned egr valve bought a new moo valve, and took a punt on VCDS
The diagnostics told me several things
No air temp sensor,
Rad fan blocked or not working P1950
Camshaft sensor reading implausible P0341
Instrument panel error P1654

Now I did a little work

I replaced camshaft sensor, and alarm persists, but no where near as much smoke on accel
I replaced rad fan, which was faulty, and now it runs constantly (grrr) and still shows alarm P1950
and replaced air temp sensor, and checked wiring from sensor to bumper-body connection,,,all good there, but the error code still is showing
And to top it all off the Mass airflow sensor is now showing up P0102

Where do I go now,
Please any helpful suggestions, or opinions, gratefully received

[niall campbell]

okay you have two coolant sensors, one for the dashboard guage/ ecu and the other for the fan to come on . So replace the one for the fan.

The engine should be showing 90 degrees after say 10 to 15 miles depending on outside temperature


New sensors can and do go faulty, go for genuine VW ones. They don't tend to be much more money and save on the muckabout factor

I am not a big fan of cleaning egr valves, it tend to lasts only so long, weigh up getting a new one and look at how long the original one lasted; but wait until you have ironed out the other faults first as they can cause the engine to run too cool

1) So check the main wiring loom for damage firstly
2) Change the camshaft sensor, air temp sensor, radiator fan sensor with genuine ones ..................................... one at a time as its too many sensors going at once, therefore maybe wiring problem or ecu / something needing resoldered
3) If you get rid of those faults, then look at buying new egr valve

[Streakie]

Thanks Niall.
The sensors were changed over a short period,
Engine runs at 90 deg,
Where is the other coolant temp sensor?
The sensors are a mix of cheap and genuine but NOTHING I have replaced works
Yeah was going to sort this wiring/electrical issue before going to further expense

Am desperately in need of an engine based wiring diagram

[niall campbell]

Traditionally cars, tractors anything really have 2 coolant sensors

One at the thermostat elbow or area , This goes to dashboard and ecu

One on radiator to switch on fan(s)

The radiator one is usually or used to be quite big & easily damaged, no tapping it on the brass face when you take it out as you tend to get aa big row for that