Both to say 'THANKS!!!' to Mat, and to say that his sensors not only work, but work exactly as advertised.
I noticed smoke from my exhaust now and again (specifically: after the engine reached operating temps and the RPM was over 1500). We had suspected a few things as the smoke had a bluish tinge but testing of the exhaust showed unburnt diesel. After several discussions and a DPF light that wouldn't go away, we ordered the new sensors. The DPF was modified slightly to prevent any restriction through it in case there was a buildup of material.
By the time the sensors arrived the car was in full-on limp mode, but without a CEL or error code. I noticed two special things about this limp mode. First, the fuel rail could never reach or exceed 14,000psi. This limited the power output and the coolant temp never rose higher than 95 no matter what I did. Second, the engine load was reporting as 100% even with light throttle. These were possibly just the ECU not bothering to calculate them properly.
Anyway, after installing the sensors, I started the car and drove off, watching the coolant temps. Shortly after the temps reached the mid-80s, the fuel rail pressure restriction was lifted but the DPF light was still on. Off we went, let the car get some speed up and wait, it's smoking again ... now heavily ... ok don't back off, 1 minute passed, still smoking, 2 minutes ... wait, the DPF light's gone out! Woohoo! Check the mirror - no more smoke!
It took about 15 minutes to change the sensors over. 14mm spanner. One sensor is mounted at the front of the DPF in the side of the pipe (white plug) and the other is mounted in the rear of the DPF in the top of the pipe (black plug). Unplug the plugs before undoing the bolts, to allow the wires to spin if they need to.
Excellent service by Mat, advice was spot on the money.
Let's say that I tried to get a hole drilled through the middle but that wasn't quite working out and in the end a vacuum cleaner was needed to ensure it was in a fit state for reinstallation.
You don't really have to worry about the two metal tubes that head up in behind the ABS unit. Mine are disconnected - either connected or not, they're irrelevant.
There are two plugs at the rear of the DPF and one at the front between the DPF and the front drive shaft. The black plug at the rear needs to come off, then take to the nut with a 14mm spanner and remove the sensor. Undo the white plug at the front and use the 14mm spanner to remove its sensor.
Replace them with Mat's sensors. Approaching 1,000km since the change on ours and it's still going fine, no smoke, no power loss and it looks like an immediate improvement in fuel economy.
So does that mean if im installing a dpf delete pipe i can unplig them, then leave those two sensors in the dpf and chuck the whole thing in the bin, and install matts new sensors into the new delete pipe?
Mine are completely corroded and locked in, no amount of blowtorch and pipe spanner will get them out
The nuts on the two metal pipes are corroded and seized too
I live on dirt roads which sped up the process of exhaust nut seizure
There are TWO sensors at the rear of the DPF. You may need the one that is closer to the side of the car (they sit side-by-side and the replacement with the 14mm nut is closer to the centre of the car). Mat may need to jump in to advise on that one. However, the other two - the one sensor at the front and the "inner" sensor at the rear - you should be able to forget about and just use Mat's replacements.
We're well over 1,000km now and no smoke. Fuel economy has settled so far at about 12.02LPHK for our typical driving which was sitting high 13s to mid 14s. The big test will be starting tomorrow afternoon when we leave for a 2-week trip with the caravan.