[VR-VS] How To: Fix the VS V6 4 Wire O2 sensor earth problem – Known Holden Problem

[chris 2012]

I recently had 3 lights come on when driving around one was fuel , overspeed and the question mark next to it and when I checked the code 12 and 76 came up , looked at the gregorys manual and had a few things which sound interesting , ive never had an oxygen sensor fail in 13 years of owning a v6 commodore , I have changed the instrument cluster from basic vs ute ( no tacho ) to a berlina cluster , swapped the cluster over to test and no lights have come up but my economy goes from 9 to 10 around town to 15 or 17 , so should I try to find which sensor has failed or just get 2 new ones ???
the spark plugs have only done 13,000kms and should do 25 to 30,000 and ive never had a bad spark plug , I might change them first but I think its more likely to be a oxygen sensor as the utes 13 years old
thanks chris

 

[ephect]

Sensors fail, that's a given. Sometimes U don't get a code. After 13 years its worth changing ur o2 sensors anyway.

Are U measuring ur consumption via the pump or the trip meter? If lights and codes have only been logged since the cluster change, is it possible to swap back for a tank to check?

 

[chris 2012]

ive owned about 7 commodores in that time and never even had an engine or gearbox failure I think there a very tough car the commodore there not perfect but no car is , measuring fuel consumption via tri metre yes , swapped clusters over now its got the berlina v6 one in and code still comes up , the fuel economy went from 9 to 10 and now uses 15 to 17 and I have noticed it will use 4.0 when idling along ( up from 3.6 litres before ) but as soon as you start accelerating it goes to 17 or 22 litres per 100kms on the instant readout , what type of oxygen sensors would you recommend ? got some prices and around 80 each from supercheap and there bosch , read online about the cheap ones for 30 or so but there cheap for a reason did think about swapping each one over and seeing if I could find which one has failed but I guess there is an easier way to find out ?
thanks chris

 

[chris 2012]

just wondering if I should buy on ebay or go to supercheap and get them ?? haven't really bought much online and not sure which seller is better to deal with , read that some sell 2 for $89 plus 8 postage and bosch , its a huge price gap between the shops and online , also with the fault codes Code 76 - Air/Fuel ratio variation between left and right banks Code 78 - Air/Fuel ratio variation between left and right banks , im getting 76 does that mean the right or left hand side sensor has failed
thanks chris

 

[VPRob]

Hi ephect
digging up this thread because I am having trouble getting a 4 wire O2 sensor working in my VP (V6). Actually running a VR motor on the VP ECU with the original memcal. Have used a VR O2 sensor and installed it in the VR position. You can read my thread here: "O2 sensor info sought" in the VN VP section.
The specific question I have is where did you earth the 50cm wire to for your fix? Is it in the cabin or in the engine bay? I figure there's not much point in doing the earth fix and not using a good new earth attachment point.
I currently have the earth return for the signal hooked up to the dedicated black wire in the harness and the heater earth secured to a bracket on the firewall so I have them separated. The mechanic shop that did the original install, including the power take-out for the heater circuit from the injector power cable, just ran both earths to a bolt on the tranny body very close to the O2 sensor at the bottom of the Y pipe. I tidied up their work and thought that running the signal earth back to the dedicated wire in the harness was going to be a sure fire fix but I still get a code 13 once the motor gets up to temp.
Anyway I am thinking that your earth fix can't hurt and may sort out my problem. If not I will move the sensor back up to the top of the Y pipe which is the VP position.
Can't do anything for a week as my VP is away with my daughter in Sydney till next weekend but researching in the meantime

 

[VSJas]

Thanks!!

I recently did this fix, (still have not replaced the sensors though) I just used a wire brush and scratched the paint off the outside of the glove box surround where a screw is attached, seems to be working well I no longer get fault 13 and I've nearly halved my consumption (ball park estimate). My ute usually only barely gets me through the week on a tank without running aircon. This week I've had aircon on every drive and have only used a little over half a tank, with around same as usual K's driven. It used to rev inconsistently (high-low), used to SLAM into drive, and inconsistent gear changes (was a real PIG to drive) now as time passes after the fix everything seems to be settling out!! LOVE my ute again!!

EDIT:
Although it seems good, is my earth point good enough??

 

[Matt02SS]

Will be doing this in the next couple of days, but just to be clear, once this is done the pink wire does not need to be cut does it? Also, if i havent got the codes listed is it something else or it still possible that this is the fault without the codes being up? Thanks in advance.

 

[ephect]

Normally u'll have the codes logged to indicate the problem, in saying that I don't believe doing this mod with hurt to try..

If U go ahead with this, U don't need to cut the pink wire, as it fixes the earth problem at the ecu.

 

[Matt02SS]

Thanks heaps mate, appreciate it.

 

[KrisG]

Just a bit of feedback. My VS started idling very roughly, almost wanting to stall some times, only on idle. It was getting code 76 and was also taking a lot longer to start. Fuel consumption has always been okay but never great.

I tinkered with a lot of different things with no improvement, so I thought I'd give this a crack.

After re-earthing at the ECU, the idle was back to normal, the fuel consumption was considerably lower, it starts up almost immediately, and overall driving is a bit smoother too.

I didn't think it'll make such a big difference, but for a simple little fix, it was well worth it. I definitely recommend doing this. Thank you ephect for this one.

I had replaced my o2 sensors with genuine replacements about a year ago, so I didn't bother doing them again after this mod, and they seem to be fine.