Our Fuso truck has thrown up it's first engine light problem since we bought it (2015 model). I borrowed a code reader and it seems to indicate NOX sensor B is the problem. I think I can identify each NOX sensor, one is before the big muffler section and one is located after it where the exhaust gasses come out. Not sure which is sensor B. Anyone understand these things? A photo of the codes on the reader. I will check wiring first I guess.
Do you have access to a service manual and a wiring diagram? Loss of communication could be a wiring issue.
No access to any service manual, but yesterday I pulled the connecter and there is voltage getting to the unit on two pins and one pin would be an earth. (four wires to the unit) I texted our mechanic that we use to service the truck and he said nox sensors failing is pretty common.
Can you post a picture of the sensor and the module its connected to? The four wires come from the sensor or the module?
4 wires from the module to whereever they go. Here is a chinese knockoff of the sensor, genuine is mercedes benz branded https://www.ebay.com.au/itm/264298806327
Two of the wires are 12 or 24 volts the other two are the data link a broken wire on either circuit will give you a loss of communication. I would check out the wiring before replacing the sensor. Can you get a diagram for that circuit from the dealer?
Thanks, I have ended up contacting the dealer and they are going to look at it. But they want two hours alone just to do a diagnostic test to see if it is the sensor as with the other codes it could be something else. Price for a genuine nox sensor $2300... Aftermarket $1000. ouch either way for an unnecessary added extra on the truck.
The dealer is telling me one of the wires is open and not sure what their plan of attack is although they mentioned cutting open the wiring harness, which I thought you would just run a new wire especially as the harness is quite long and in a horrible spot. The voltage to the sensor is only supposed to be low. 2-3V max. So you were right with the broken wire.
The broken wire is probably near the exhaust treatment system. The heat makes the insulation brittle and it cracks then corrosion sets in and dissolves the copper.
It is fixed now, I did not look hard but there was some fresh tape where the NOX sensor is. Reading the repair report there is a 24V line and that was the one that was broken. I should have asked them just to remove all the emission crap from the system and be done with it. We have an old UD truck here. over 400 000 km and it will be 40 years old next year. Never really let us down.. Ever. Just routine services.
Yeah, same. I've got a 25 yr old Isuzu with 500k, I've replaced the waterpump and thermostats in the 15yrs I've owned it and that's it. My new Fuso is out of warranty middle of next year. Its done more km in trips to the dealer for warranty than its ever done carting cattle. Unfortunately I think it's just the way things are now.
We have had a good run so far with ours. This being the first real issue. As time goes on I expect more things to start popping up.