Hi all,


I need a logic check here. I had a P1647 code come up leading me to change all 4 sensors. I used Denso sensors that came with the correct connectors. The fault is still there....


So, I figured the problem is in the wiring. I checked the continuity through the connector and had no problems. I printed out the wiring diagram with the intention of tracing the wiring all the way back to the ecm. So as a last check I switched the connectors bank 1 to Bank 2. The fault switched sides becoming a P1646. To me that indicates that the problem is the sensor itself and not the wiring...doesn't it? I'm not a fan of coincidences so it seems strange that I'd buy a bad sensor and install it in the same position but it was a 50/50 chance.


What do you think? If it could be the sensor, do you have any idea what the resistance across the terminals on the sensor should be? I still have the old ones and can test them as well as the ones in the car...


Thanks in advance...

 

Heater circuit around 1ohm.

Obviously check relay(s) & fuse(s).

 

Thanks for the reply....Can you direct me to where the fuses and relays are?


I checked the old sensors... on one I have 8 ohms across two terminal, open circuits ever other combination. The other sensor is open circuit everywhere...


Take care,

 

Did you clear the codes with your machine? Have you performed a hard reset?

 

I've done both. First with the scanner and then with the hard reboot. The CEL comes back with the first restart.

 

Bruce have a look through this for the location of all fuses and relays - a handy document

Also try 1 terminal and earth to car. It is possible to get a doa sensor but remote.

 

Thanks, Sean, I'll try that. I'm having trouble with the idea that the new sensor could be bad. I know it happens but it has to be rare. And what are the odds I would put the bad one in the same hole as the old bad one? ( I know, 1 in 4...chuckle)


What's pointing to a bad sensor to me is when I switched the sensors right to left. The fault followed the change. If it were the wiring it would stay associated with the same position...or so I think.


I'm thinking of putting a 1 ohm resistor across terminals 1 and 2 to fool the ecu into thinking the heater circuit is there. This wouldn't be permanent, it would just be a tool to prove the point. What do you think?


Thanks again!

 

You'll get codes, I expect. Not sure which ones but might be for bad heater (as its ohms should increase as it gets hot), might be for cat (since fuelling will be wrong), might be ... well - let us know

Careful to use a fair wattage!! It'll get hot or burn out otherwise...