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

[ephect]

More Pictures will be added later, this is all i have so far...



DISCLAIMER: This a guide only, by following this process I take no responsibility what so ever. If you bodge it, fry your ECU or your car turns into a troll and consumes your insides. You do so at your own risk. Now with the formalities out the way... let’s begin


The Problem: The 4 wire oxygen sensors include an internal heater, which aids the sensor to reach operating temperature quicker than relying on the exhaust to heat up the sensor. The heater circuit interferes with the signal received by the ECU from the 02 circuit, due to both circuits sharing the earth. This is the main fault for increased fuel consumption, and often fault codes logged:

Code 44 - RH Oxygen Sensor Lean (O2)
Code 45 - RH Oxygen Sensor Rich (O2)
Code 64 - LH Oxygen Sensor Lean (O2)
Code 65 - LH Oxygen Sensor Rich (O2)
Code 76 - Air/Fuel ratio variation between left and right banks
Code 78 - Air/Fuel ratio variation between left and right banks


The Solution: To earth both circuits to a good solid earth point on the chassis somewhere, then replace both existing O2 sensors with genuine new items. Even if you have recently installed new O2 sensors, these might have been prematurely failed without logging an exact code. If you want to see the full benefit of this fix, replace your O2 sensors after completing the earth fix. Example: I completed the earth fix, drove around for 2 weeks prior to installing the new O2 sensors and my air/fuel gauge showed varied results, immediately after installing new O2 sensors instant readings of 14.7 displayed.

This guide recommends new O2 sensors with the fix.

This guide replaces the need to cut the pink wire! if you have cut the pink wire, my advice is to follow this guide and fix the issue properly.


What’s needed:
* Common Sense, I know we all have some
* Soldering iron & solder
* 10cm length of wire
* 50cm length of wire
* Side cutters
* Small pointy nose pliers
* Stanley knife or blade.
* 1x Ring electrical connector (crimps on wire and looks like a loop/washer)
* Electrical tape (normally I would suggest Heat shrink, but we aren’t cutting wires)
* Screw drivers both flat and star
* 2x New Genuine O2 sensors: Part #25312184
* Couple hours and a couple of cans


Here’s how to fix up the earthing issue

Gaining access to the ECU
* Undo the 3-4 plastic screws underneath the glovebox between it and the firewall.
* Open the glovebox
* Remove the black pin on the right hand side
* Gently remove the glovebox compartment.
* Open the passengers door,
* Unscrew the 3 screws in the vent (dash side, not the door vents) and 1 screw visable under the end of the dash where the glovebox hinges on the left hand side.
* Using a small screw driver, lift the beeding on the door sill and peel it back about a foot.
* Gently remove the kick panel by pull the bottom in the centre, the back will pop out first, then prise the door seal out a little to let the side of the kick panel out. Lift the sill panel up and the kick panel should pull away.
* using the small flat blade screw driver, lift the tabs at the sides and bottom of the ECU to release it from its holder.

Fixing the Earth at the ECU

Disconnect your Negative Battery Terminal prior to carrying out any electrical work.

* locate 3 black wires
- 2 wires on 32pin blue plug, pink socket – D14 and D16
- 1 wire on 24pin blue plug, pink socket – A2

* Strip the 3 wires back using a blade by ringing the insulation (slicing around) in one spot, then ringing it again 5-8mm below it. Then u can slice along the wire from ring to ring and peel that section out.

* Get your 10cm wire and strip 10mm from both ends
* Get your 50cm wire and strip 10mm from both ends
* Twist one end of both 10cm & 50cm together (don’t solder yet)
* Twist your joined wires around both D14 and D16.
* Solder the 4 wires, then wrap with electrical tape.

* Wrap the other end of 10cm wire around wire A2
* Solder this together and wrap with electrical tape.

* Crimp on the loop crimp on electrical connector to the other end of the 50cm wire and solder the wire to the connector for good measure.
* Locate an earth point on the chassis, clean it and then screw the loop connector firm.

Put back the kick panel and glove box together by reversal of the above. Install your new O2 sensors and your done!


References: I have results and all pre testing prior to providing this how-to in this thread: Too lean on one bank


Cheers
ephect
.

[ephect]

post #2 reserved

[S2_VR_]

hey buddy...how do i get the ECU out of it's holder?...im stumped....also im trying to do it in semi dark conditions...so i'll try in the morning

[ephect]

lol all good mate, its kinda hard at night as the holder is black. get a bright torch!

a little tip do the sides first, as the bottom tabs get caught on the casing screws. from memory there are 6-8 tabs 2 on each side of the casing (cant remember if the top has tabs also)

[VS_Pete_1]

Great write-up mate.
And good pics.
Thanks 4 that.
Can you come around and do mine

[VSIIBerlinaL67]

can you just install the 2 wire sensors from the vt and vx's? and get rid of the heater all together?

[alex2_s]

can you just install the 2 wire sensors from the vt and vx's? and get rid of the heater all together?

very early series 1 VS's had a 2 wire sensor then it changed to 4 wire, as did the wiring connector on the ECU side of the sensor to accommodate the 4 wire... so I'd say the 2 wire plug wouldn't fit the new 4 wire connector??

[ephect]

Great write-up mate.
And good pics.
Thanks 4 that.
Can you come around and do mine

LOL thanks mate, send me the flight details and i'll pop over

can you just install the 2 wire sensors from the vt and vx's? and get rid of the heater all together?

the heater in the O2 sensor is a great idea, just they stuffed up a little with the wiring. most of the time i get instant readouts on start up (after this mod) and i know when the ECU is still in open loop. I'd cut the pink wire about a year ago which disables the heater, but i should have earthed the o2 circuit along time ago. keep the heater, a real benefit over the non heated.

very early series 1 VS's had a 2 wire sensor then it changed to 4 wire, as did the wiring connector on the ECU side of the sensor to accommodate the 4 wire... so I'd say the 2 wire plug wouldn't fit the new 4 wire connector??

correct on the early commodores. you could rewire a 2wire o2 sensor to plug into the 4wire plug on the loom, but for the hassle every time you replace the o2 sensors, not worth it. do the mod, keep the heater

[holdenrocks]

hey, i have issue on o2 sensor and i just got oxygen sensor replace 1 month as i found there have no signal on the scantool, as didnt get any faults code. sound like need to replace o2 sensor again or get bad earth or what ??? thanks

[ephect]

Hi mate, being a VR i cant guarantee that this fix will work. does your o2 sensors have 2wires or 4?

[holdenrocks]

4 wiring o2 sensors. but in ecu there have 2 plugs connect not 3 plugs connect like vs ..

[ephect]

sorry mate, i dont have any wiring diags for the VR ecu atm.

[Slippy_Trippy]

So main benefit of 4 over 2?

I have the 2 wire version and wondering i it's worth the effort to look into putting in the 4 wire.

Cheers

[delcowizzid]

4 wire just starts reading earlier due to it heating faster and also stays at a hot temperature.they are good if you have gone to extractors and have the O2 sensor further down the line than normal as they can cool when idling at lights and at gentle cruise from not enough exhaust heat.putting them ins easy it just requires 12v from switched ignition so it turns on when the engine is about to start and earth as well as the 2 feeds to the ecu you allready have

[Tom_1569]

Just thought id say I did this fix by following the workguide.
My car hasnt blown up and it seems to be working fine. Im yet to replace the o2 sensors (thanks Auspost) but it seems like a solid idea.

[aceventura]

Sorry to dig up an old thread. I am in no doubt the above how-to works well, I just want to understand a little more about it

1) I was comparing the wiring diagrams in my Gregory's to that posted on Dr. Bobs website. They are quite different (attached is my interpretation, with the fix show above by dotted lines on the right hand side). The wiring diagram in the Gregory's manual is actually very similar to the fix described here, except for the use of pins A1, B1 and B2 in the Gregory's manual (which are not present in the other wiring diagram). Did Holden fix the wiring problem in later models (Series II or III)?

2) I am no auto-electrician, I can only barely understand the wiring diagrams, and I don't understand the origins of the current leakage. However, I was wondering why you couldn't splice directly into the negative heater wire at the loom in the engine bay and run an earth directly to the block?

Thanks for any help.

[immortality]

the current leakage issue occurs because both the sensor and the heater part of the O2 sensor share earth connections. this is bad. the problem is somewhere inside the loom and would require unwrapping to find the earth wire links. in later models i believe holden kept these earths seperate so no more problems

removing the earth wiring for the heater from the loom and earthing in the engine bay is a good idea. i'm working on this mod when i've finished this post. i'm making a tempory connection in the engine bay untill such time as i can mod the wiring loom properly.

[aceventura]

Thanks Immortality - let me know how it goes.

[nathanVY]

hey is this an issue in the VR v6 as well?
i'm keen to try it except i dunno how ill go stripping the ecu wires, id definitely break them!

[nathanVY]

anyone know?

[delcowizzid]

only a vs problem im sure

[nathanVY]

says vr-vs in the title lol

[fonzo]

i went and got myself. a butane soldiering iron. a kingkrome folding pocket knife. some wire. bit of other shit cost me a 100 bucks but i use it for tafe anyway. had a dip at it. deffently workd LOL...went from 18 litres per 100km out on the open road at 100km.. to this.

thats in the city with the air con....stayed this for atleast 100kms around the city.

[fonzo]

i was givin it plenty of stick too

[ephect]

says vr-vs in the title lol

ah sorry mate, its part of the defined drop-down for the model range

i went and got myself. a butane soldiering iron. a kingkrome folding pocket knife. some wire. bit of other shit cost me a 100 bucks but i use it for tafe anyway. had a dip at it. deffently workd LOL...went from 18 litres per 100km out on the open road at 100km.. to this.

thats in the city with the air con....stayed this for atleast 100kms around the city.

awesome! good to here it gained you some decent results.