When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I had a similar issue, replacing the sensors numerous times because of codes. Every new sensor seemed to be dead on arrival, despite the Rover running fine.
There is a grey multiplug on the inside fender on the passenger side. Apparently it gets dirty and screws with the electrical signals. I cleaned mine out and I have been code free for 2 years.
I focused on the top part where the wires went into the plug. I used compressed air & electrical cleaner.
It only takes a minute to do, and is worth a shot.
I started getting P0155 pending codes, no SES light.. tested the Heater Circuit on the installed O2 and it read as open(goofed apparently), bought new Bosch OE upper O2 sensors and started getting p0155 and p0153 codes fully setting off the SES light. Rechecked the original and it's resistance was about 2.5ohms and the new were about 2.0ohms. I checked the driver side before ordering new O2 sensors and was getting battery voltage. Pulled this connector, which is LOCKED together by the metal bracket, and there was a spot of corrosion. I cleaned it up, added some grease to try to prevent corrosion later and will drive it tomorrow to check codes..
On my Toyota I am able to read Catalyst temperature, I'm assuming that's from the O2 heaters(?), from Torque and an OBD adapter. Does anyone know if we should be able to see the same?
Note: Pin 14 in plug C0203/C0449 is power to ALL of the O2 heater circuits, the rest of the o2 wires go straight to ECM plug C0635
Last edited by Sandman614; Mar 2, 2021 at 09:42 PM.
No luck on cleaning that connector. I checked that all the O2 wires made continuity between the O2 plugs (The honda extensions work great for this) and the ECU plug C0635 and all of them checked out good. When I put it all back together the Driver side was reading correctly while the Passenger side(Bank 2 reading in Torque) was reading a flatline 0.45v, even disconnected. This morning I rechecked power at the O2 plug which was fine, rechecked resistance of the O2 heater circuit which was about 4.5ohms HOT, still flat lined at 0.45v... I reached under the dash to make sure I plugged in the ECU connector and when I bumped the wires the O2 sensor started reading again.
Soo... wiggle the wires on the ECU plug C0635 and see if it makes a difference?
OP The only things that are common between all 4 O2 sensors are the power wire to the O2 heaters(F2 fuse, C0203/C0449 connector, distribution joint under the back of the upper intake(?)), the exhaust pipe/gasses, and the signal wires in ECU plug C0635
Last edited by Sandman614; Mar 4, 2021 at 12:27 PM.
