ECU O2 sensor fault - 2006 v6 4motion

[jas4motion]

Hey guys, i recently had my 105,000 service and after a check engine light very vague diagnosis for possible faulty O2 sensors at the dealer I took my car to Lawrence at German Autos at Geebung. turns out the issue is with the ECU sending a low voltage to the O2 sensor heating elements, or at least that's what I think he told me He's looking more into it & checking tech forums for a fix, hopefully just a software patch or something? But its not the actual sensors & its also not the wiring for the sensors. Has anyone else had anything similar happen with their ECU? A new ECU could cost me a couple of grand which is not something I'm keen on at all & is freaking me out a bit. The car runs perfectly even with the fault light on.

Any help or advice would be appreciated, Lawrence really knows his stuff but I'm just looking for some insight & experience from you guys too. I have an aftermarket warranty with Garry Crick VW on the Sunshine Coast but they told me it doesn't cover sensors & they're an hour away from me in Brisbane. I'm waiting to talk to them as to whether I'm covered for a new ECU if I need one?

Cheers

Jas.

[vdubmotorworx]

if the fault code is a 02 sensor heater element fault it will be the sensor itself...very common on golf 4/bora... especially on the 2.0L engine. The element for the heater control internally fails.....sensor replacement mate....VDUB...

[jas4motion]

Thanks, I'll pass it on.

[Transporter]

A good mechanic should be able to reliably diagnose the oxy sensor, so I don't believe that he would be replacing the ECU when the Osensor is healthy.

[jas4motion]

Apparently the fault is being caused by low voltage from the ECU to the o2 sensors which is in turn registering a fault & thus the check engine light.

[vdubmotorworx]

I find that strange.....VDUB...

[jas4motion]

Both heating elements in O2 sensors are working ok. Both draw same voltage as a new sensor. But that reading is verly low, about 0.6, should be a lot higher than that but the handbook doesn't list what it should be so currently trying to find that out by checking with the same model as mine that's coming in tmrw. It's either the driver in the ECU or the wiring between the ECU & sensor, from what I can gather.

[buzuki]

have you considered that the sensor may be shorted to ground inside and hence the 12v you expecting to see is now a near earth .6v

Ill put my money on the sensor. Ive replaced stupid amounts of these on this engine

[Umai Naa!!]

Agreed. I'd start with the sensor.

Cheaper and easier to replace than the ECU. I wouldn't rule out the ECU, but I'd be replacing the sensor first.

[vdubmotorworx]

anyone that has worked on mk4 golf.bora.beetle time served would have a quick visual of wiring and air leaks etc but then whack a new sensor on it especially with a "heater element" code logged...VDUB..

[jas4motion]

Getting the car back tomorrow with fault still there. I asked the question "it's definately not the sensors" and the sensors are fine. Current sensors drawing only .6 amps after 1 hour that went up to .8 amps each total draw for both sensors was 1.6 amps. Plugged in a brand new sensor and the new sensor still only draws .6 amps.

So if the fault light is being actiavted by low voltage between the o2 sensors and the ECU and a new sensor still delivers the same fault would that still mean it's a faulty sensor?

I'm happy to bring it to someone else for diagnosis and repair.

Cheers

Jas.