The new sensors, are the definitely Denso parts bought from a trusted source?

 

Yes $200 each from O'Reilly

 

Since both upstream sensors are showing the same heater fault, check the 15A A/F Heater fuse and the A/F Heater Relay.

Aside from a fault in the wiring harness. these are the only components that could simultaneously affect the heater circuits both A/F sensors.

 

In that case, hopefully then the issue is what FJ said, the fuse or the harness.

To check the harness, unplug the sensors and unplug the engine ECU and test the wires using an ohm meter (look for the same color wires at the ECU connector).

In this link scroll down to page 70 for the engine ECU wiring diagram to guide you:

http://www.lastgreatroadtrip.com/wp-content/uploads/2008/03/2007-toyota-fj-cruiser-electrical-wiring-diagram.pdf

The O2 and A/F sensor wires are shown on pages 75 & 76. They are described on page 82 and their pin locations are detailed on page 83.
Norm

Sadly a check of relay (swapped with know good one) and new fuse DTC return. Thank you all the hunt continues.

 

In that case, hopefully then the issue is what FJ said, the fuse or the harness.

To check the harness, unplug the sensors and unplug the engine ECU and test the wires using an ohm meter (look for the same color wires at the ECU connector).

In this link scroll down to page 70 for the engine ECU wiring diagram to guide you:

http://www.lastgreatroadtrip.com/wp-content/uploads/2008/03/2007-toyota-fj-cruiser-electrical-wiring-diagram.pdf

The O2 and A/F sensor wires are shown on pages 75 & 76. They are described on page 82 and their pin locations are detailed on page 83.
Norm

 

I wish to thank all who offered ideas the offending relay has been sent to a re-education camp and new part installed 😀 much thanks

 

Your posts #6 and #7 seem to conflict ... did the new relay resolve the fault, or did it re-appear after clearing the fault code?

If a new relay/fuse did NOT resolve the fault, then you're going to have to study the electrical schematics, get familiar with the sensor heater circuit, and check ground and B+ supply at the wiring harness connectors at each air/fuel sensor using a multimeter.

 

Got it, thanks for the closure.