Oxygen Sensor Problem Recurring

[Theaviator2011]

Hi Everyone,

Hope somebody might have an idea. About 8 months ago received an engine light + rough running. Did the bridge pin method and determined a code 44 (Oxygen sensor sending a lean signal to ECU). Changed both sensors with a Bosch set and it worked OK for 6 months until suddenly, the engine light came back on again + rough running. Same error code. Changed the Oxygen sensors over again with a new Bosch set. Within 3 months, same problem again - engine light + rough running. Same error code. Not sure what's going on here but I am thinking that it is not the Oxygen sensors and it is something more serious.

Has anyone had this problem?

I started the car this morning and no problems. No engine light and the engine was running smoothly.

[James39]

Could be a bad earth for that sensor.

Other things to check would be your CAS and DFI, fuel injectors

[Brett_jjj]

The 02 sensors both earth at the front of the engine.You can see the black wires and the connectors on the bolt on the heater pipe outlet.Make sure this earth point is clean and tight.Ive also added a thick battery cable as an extra engine earth cable,it goes from the negative battery terminal to this same bolt on the heater outlet pipe.

[RX25SE]

I rewired the earths at the PCM.

[Not_An_Abba_Fan]

Code 44 is RH sensor lean, which could indicate the usual VS sensor problem. There are two fixes, one is to cut the pink wire on the car side of the sensor plug, the other is to rewire the earths back to the PCM as RX25SE has done. There is a how to done by ephect for this.

The issue is the heater wire interfering with the signal wire and sending the dodgy signal.

[Theaviator2011]

Thanks for your help guys I managed to cut the pink wire on the loom side. No more engine light but here's a strange thing. When I drive the car around during the test drive - and bring it back to a stand still with the engine still running, it actually begins to run quite rough again but no engine light comes on (as it did before I cut the heater wire on the loom side of the Oxygen sensor) - and this occurs for about 15-30 seconds and it begins to idle smooth again. I then drive it around again, no engine light appears, then bring it to a stand still (again), it runs quite rough and within 30 seconds or so returns to a smooth idle. This is really strange!!

Any ideas?

Regards,
Brad

[Not_An_Abba_Fan]

Could be totally unrelated, but it could also be the O2 sensor.

Clear the codes by removing the engine fuse and turn the key to on, then off. Take it for another drive and check for codes again.

[Crisis63]

Same problem with my CV8. Put on extractors (Pacemaker) and the problem occurred. They showed up “slow”. I replaced them and had the codes cleared and the new ones showed they were only delivering a default current, not working. Checked the fuses and they are all ok. At a loss at the moment.

[Theaviator2011]

Hi Guys,

Just to update everyone. I took the car into a Holden service centre and they checked over it and the rough running appears to be coming from cylinder 3 - they did a compression test on this cylinder and it is running OK. Holden have not taken the rocker cover off yet so they cannot be certain but seem to think that the problem is with a sluggish valve spring or perhaps a faulty rocker or pushrod for cylinder 3. The inlet valve is not opening fully and therefore leaning in that cylinder, which in turn is setting off the oxygen sensor for that bank. They also think it could be the injectors.

They checked the leads and resistance is within tolerance
The plugs have been changed
The MAF sensor has been checked and is OK (according to them).

Looks like I'll be selling it... This is an example of where the cost of the exercise would outweigh the benefit.

Brad

[Not_An_Abba_Fan]

It may have broken a rocker arm, revving ecotecs hard tends to do that.