Ok.

So I've got a 2015 Vantage V8S

Performance upgrades:

Velocity 200 Cell cats
Velocity Headers
Dual Plate Clutch with Lightweight flywheel.
Velocity ECU tune.

Car ran fine after the upgrades (fall 2018)

The car started throwing codes at around 25k Miles (spring 2019-summer)

Codes were:

P0130
P0150

(of course, the check engine light appears along therewith)

Based on the foregoing, both upstream O2 sensors were diagnosed as going being and hence they were replaced (this past Friday 9/20).

With the new O2 sensors in place, the car is still throwing codes, i.e., drive for an hour and the check engine light comes on, especially at low speeds (think pulling up to or away from a traffic light).

The codes, this go round, are appearing for one bank though. My sense is that if the ECU tune needed a tweak, codes would be thrown for both banks.

With the new O2 sensors, I'm now getting:

P0130
P2195
P0131

Perhaps, the O2 sensor came out the box bad?

Thoughts?

 

It could be that with the new cats the cars O2 sensors aren't picking up the results they expected, I know with other cars I've had with sports cats that a resistor had to be inserted into the O2 sensors loom - maybe contact Velocity and ask them?

A problem I had when I first started driving at 17 (definitely not an Aston!) was that the ECU read issues at the O2 sensor but in fact it was the MAF sensor that had failed, so the car was using the wrong readings coming in and therefore the fuel mixture was incorrect hence the O2 sensor showing the error; another thing to consider.

 

Just to close out on this.

The eventual culprit turned out to be a cam cover O-ring. In short a leak at the cam cover vent, which caused the engine to run lean. This required a smoke test to find (recommended by AM Aftersales).

All O2 harness extensions were also replaced, because some of them were melted. As a precaution, the new O2 harness extensions were wrapped with heat sleeves to safeguard them from the exhaust heat.

All in all, this one was a bit pricey but all-in-all most issued were sorted.

Thanks for all the responses