I had a p0135 come up the other day which I believe is bank 1 sensor 1 o2 sensor heater circuit. I also have off-road headers with no air pump with p0410 sometimes and just p0140 p0160 for rear o2s deleted. Does this mean that the one o2 sensor could be bad? That codes not related to the p0410 air pump for cycling fresh air or whichever to the o2 sensors?

 

You will need to check power and ground on the O2 sensor harness side with key on...you can just use a 12 volt test light to check power and ground.(ground is checked with test light connected to battery positive)..the heater circuit are the same color wires on the sensor side so match them up to where they go on the harness end...if you have a scan tool you can check to see if the heater circuit is working...pull the heater circuit fuse and with the key on you should see a 450 mv bias voltage...if you see that 450 mv bias voltage plug the fuse back in and see if the millivolt reading drops below 200 mv after about 1 minute...you should also ohm out the sensor heater circuit (the same color wires)...you should see between 3.5 to 14 ohms…picture of heater circuit wiring and resistance check below...I am now in the process of changing all 4 of my O2 sensors and 2 NEW upstream ones were bad out of the box...I used a heat gun and a DVOM to measure the millivoltage at 1000 degrees on the new ones and they check out OK so I am confident these Bosch O2's will work...the bad ones were Delphi which I purchased from Rock Auto.

 

Great so check the two purple and lighter brown colored wires on the left with a test light from the plug socket with a probe meter will read if it has 12 volts or exact voltage worst case a working test light if I have one? Then go ahead and test both brown wires on the o2 sensor with multimeter dang you bet I got 24" or extension harness for headers. I had just finished ziptieing everything for the second time after installing headers a couple months later figured out the kick down racket was the torque tube had to drop them again.

 

No !!…the heater circuit are the 2 brown wires and the other 2 are for the signal circuit…like I had said see what 2 wires on the harness end connect to the 2 brown wires…you should have 12 volts and ground on those !!…also check the resistance on the heater circuit.

 

To check to see if the FRONT 02's are working correctly you can use most any good quality scanner
When working properly the front 02 voltages should have an AVERAGE voltage between .400 and .550 millivolts-------- The lower the average the leaner it runs during P/T or closed loop--The larger the average the richer-------ALSO check your LTFT fuel trims----They should always read slightly negative or "0" You never want a POSITIVE fuel trim---A tuner can sort this out for you with MAF corrections IF your 02 voltages are in spec--

 

I erased the code and hasn't came back. I'll check it with a test lite and multimeter next time i get under the car. Thanks for the information. So we are checking that both brown wires from the engine harness with a test lite read 12 volts and on the o2 sensor check both brown wires for correct mv?

 

This is how the voltages appear on my car when engine is started. Voltages drops on the front O2's until they start moving aroun 0.45 volt when the car get into closed loop .
When the cats are hot the rear should stabilize on 0-7-0.9 volt if the cats are OK .

 

Are you saying you have to check it with the car running? The heater circuit varies from 4.2-4.3 is this within range of where it should be?

 

It is done Key On Engine OFF...if you are reading 4.2 to 4.3 ohms that is good...as in the picture for B1S1 you should see system voltage on the brown wire (far right) and the black wire next to it is ground !!...I am currently in the process of changing my upstream sensors for the 3rd time...2 bad Dephi sensors from Rock Auto and 2 bad Bosch sensors from NAPA...I will try again tomorrow...so beware of new parts !!...Dude, you need a new IPhone 13 like mine to take clearer pictures...LOL !!