Check Engine light comes on after reset..

[JMCLuimni]

Car starts fine. After I drive the car and temp gauge gets to about the 12 o clock position, normal temp, the CHECK ENGINE, light comes on. Car appears to drive fine but there is the slightest roughness at idle.
After checking faults using the PEAKE R5 diagnostic tool I get fault code for both O2 sensors. Both o2 sensors have been replaced and I still get these faults. Car idles fine until temp gets to normal range then the CE light comes on and a slight rough idle.
The cars history shows that the right bank O2 sensor has been replaced 2 times over 60,000 miles so there is a bit of history to this. Car had sat for 13 years prior to me getting it. CE light comes on only when temp gets to normal range after resetting it.

[jclausen]

With out knowing the exact fault description I would be t you have lean faults and the oxygen sensor would pick that up, but the oxygen sensor is not the problem, you would smoke check the intake system looking for a vacuum leak.

[JMCLuimni]

Question:
Why would the O2 sensors wait until the exact time that the engine temperature gauge gets to the 12 o'clock position before triggering a CHECK ENGINE light if this issue were a vacuum leak? Wouldn't the CHECK ENGINE light come on once the vacuum leak was detected at start up or shortly there after? (As an aside I use the PEAKE to reset the CEL after each illumination).
I haven't done the "smoke test" as I'm not familiar with the process or tool requires to generate smoke.
I have cleaned the MAF, checked the hoses from the MAF to the engine and all appear fine. The car does have a documented history of CELs being triggered by O2 faults (there have been 3 separate instances where O2 sensors were replaced by dealer over a 20,000 mile period (between 41,000 and 62,000 miles). Car currently has 62,125 miles.
PEAKE only gives me both O2 faults and so too does the stomp test.
Any guidance is appreciated...

[shogun]

jclausen asked this question: What is the exact O2 fault from the Peake reader?

Oc oxy sensor #2
Od oxy sensor #1
25 oxy sensor heating relay
C9 lambda control #2
Cb lambda control #1

any other faults?

[JMCLuimni]

Faults read
Oc O2 sensor #1 and
Od O2 sensor #2.
Faults only come on after engine heats up to 12 o'clock position. Those are the only 2 sets of variables....

[JMCLuimni]

Codes read are on diagnostic machine are 1221 and 1212... both related to the O2 sensors and both come on at operating temp only.
A member here suggested a bad EGR valve, would this ring a bell to anyone? Im thinking it could be the ECM but am open to suggestions....
Anyone have any ideas to help troubleshoot this?