Keeping busy as usual
It will be interesting to see if the replacement lambda cures the fault. I come across loads of these kinds of faults through work speaking to mechanics every day. The problem with lambda fault codes is whether they are the cause or the effect of the problem. We have a new system at work which has been developed by Carweb and is now exclusive to GSF. It has been designed by mechanics and tech people alike to outperform autodata and is taking the industry by storm behind closed doors
If a replacement lambda doesnt cure the fault then if you PM the P code for the fault i can input this into the system and it will walk me through step by step all the possible causes of that code on that vehicle and include how to investigate each avenue. It really is very special in its capability...so much so that autodata have taken the hump in a big way
Im pretty sure i can email the processes aswell.
Im not sure what other sensors are involved in the induction, ecu and fueling system on that engine but often the lambda fault pops up as an after effect of the original cause. It being intermittant definately points towards an electrical issue at some point. Often with these faults, the air mass readings become "unclear" to the ECU....usually air mass sensor or intake manifold pressure sensor if fitted. In these cases the ECU not being entirely sure of the volume of air entering the engine, makes its best guess and tends to overfuel to ensure the vehicle keeps running to get the occupants to their destination. Soot, rich fuel smell and poorer mpg's tend to follow. Emissions are then thrown out of normal levels and if run like this for a long time the lambda in the system, being forced to work outside of its normal working range, tends to either throw up the fault code or fail entirely.
I might be wrong, but thats how most vehicles i come across tend to be behaving. Your ocilloscope would probably come in handy testing individual sensor performances if you cant remotely test them with the lexia.
It will be interesting to see what cures it....