'01 Rx300 Healed Itself: Is This Possible? Normal?

[ZAPP]

Friends

This concerns my 01 RX300 2WD, 78,000 miles.

Awhile back 'outta the blue' while driving one sunday evening I got the Check Engine Light & the other two all 'on' suddenly, and subsequent checks showed one error, P1135, heater element of A/F Ratio/O2 Sensor 1 Bank 1. Both O2 Sensors are new, having been replaced in the past year. No code up to that point.

I pulled the code with my OBDII and cleared a couple of times but it came right back. I tried unsuccesfully to get to the Connector [how DO you guys get to that thing????] to see if cleaning the contacts would help anything. Well, two days ago, while driving about 5 miles from my home, the lights suddenly went away. No code left. Later, it all came back again [same day], and then just as strangely went away again. Since that time the condition has not recurred.

WHAT set of circumstances can cause the correction, especially while the engine is running... sorta "on the fly" ? I could maybe theorize it if the OK came at startup - but I'm baffled by what happened.

Any help would be greatly appreciated. I must say I am suspicious of the ECU or whatever device it is that first collects/parses the inputs from all over the vehicle.

zapp

[wwest]

SOP...

The connection simply proved to be only intermittent.