Oxygen sensor issues / ecu to O2 wiring

Ok,
All earth points tested, cleaned, worked, cleaned, and tested again. <0.1 ohm
Battery terminals cleaned and checked.
Positive terminals checked & cleaned in fuse box (100amp+ connections)
Removed and inspected ECU, confirmed O2 sensor ground path to earth.
Confirmed harness connections for heater, ground and sense wires <0.1 ohm
Confirmed all connections to earth connector block for left and right a pillar <0.1 ohm.

Test drive, after warm up, left (bank A) sensor reads 0V on Nanocom and reads -0.8V on a good multimeter, right (bank B) sensor reads 0V on the Nanocom most of the time, with the occasional rise to 0.3V (haven't put the multimeter on this side yet).

Next I'm going to swap out one of the new O2 sensors with an old one that works, if that doesn't change anything it might be ecu replacement time.

Cheers
Marc

I think I have a win!

Replaced the negative reading O2 sensor on bank A and Its reading normally, it's even improved the bank B O2 reading, although I'm still not happy with that one either as it seems a bit slow and reads lower than my old O2 sensors.

So I believe I have a reverse polarity NTK O2 sensor, which might have been upsetting the ground feed for both sensors. The other sensor still causes an error code for being too low so I might have to get both replaced

The NTK sensor may just have the sensor wires reversed in the plug. Try swapping the two pins over. Just make sure that neither sensor wire is earthed to the sensor case. The wiring colours on sensors can be a bit erratic but generally the heater wires are plain white and are not polarised. Just swap the other two over.

Just to close off on this issue:

The NTK oxygen sensor was sent back for replacement due to reverse wiring (-0.85V), the second O2 sensor was an inter-motor brand and was reading lower voltages than an old Bosch sensor (+0.75V max), this was also sent back for the low output.

Paid more and got two genuine Bosch sensors both read a solid +0.91V max.

Result:

Petrol economy down from 22.5L/100 to 16.5L/100
LPG economy down from 27.5/L/100 to 20.5L/100

Cheers
Marc

Quote:

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Originally Posted by Mattblack59bus

Just to close off on this issue:

The NTK oxygen sensor was sent back for replacement due to reverse wiring (-0.85V), the second O2 sensor was an inter-motor brand and was reading lower voltages than an old Bosch sensor (+0.75V max), this was also sent back for the low output.

Paid more and got two genuine Bosch sensors both read a solid +0.91V max.

Result:

Petrol economy down from 22.5L/100 to 16.5L/100
LPG economy down from 27.5/L/100 to 20.5L/100

Cheers
Marc

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Hence I asked earlier what brand of O2 sensors as Non Bosch can cause problems.
Regards,
Mario