Replaced the bad o2 sensors and it solved the issue.

 

I had c5 diag help me the last time I seen p0135. He said check for 450mv on the o2 sensor one side two wires and check for 12 volts at the plug or o2 harness connector to make sure it powers the heater circuit. The p0154 is insufficient activity on the right bank sensor. Maybe it's time to replace o2s as the car has 92k miles. It has new o2 extensions with the tsp headers. I cleared the codes twice they came right back. It is in the lower 50s, 40s whatever that means it it's colder and whatever the heater circuit pertains too. The only problem I see is that all AutoZone o2 sensors any brand are warrantied for 1 year. The last time I bought o2s for my 98 z28 with slp headers in 2009 were from Napa Bosch Corvette rear o2s for 42$ each vs buying extension harness as the car had 12x,000 miles on it and could use the new o2s never gave me any problems with the headers, cam or 500whp turbo s475 until the engine thru a wrist pin out side of the block boosting in 4th at the track at 169k.

 

well i reset the codes this morning i had the carwash eat 5$ and 50 cents so i had to return there with the car wash operator to get a refund. The codes haven't came back yet maybe something caused when the weathers colder. I have a few delphi used o2 sensors i can try if the codes come back if they test 450mv and get a chance to confirm the heater circuits are getting 12 volts before determining there bad 92k mile o2 sensors.

 

bad o2 sensor

 

Do you have a scan tool and what exactly do you want to check on these O2 sensors ??

 

I was battling a o2 issue and to check volts on sensor is put sensor in a vice and get a heat source troch. When its heated up u should get a value around 1v. When u take heat off it should fall quickly back down. If it holds a steady number its bad.
There is an internal volt source dont ask me how.

 

No i dont have a scan tool this weirdo in law has one that reads o2 activity live data found out he had a dead o2 on a dodge journey 2014 my sisters husband but i dont mess with his stuff or wouldnt ask him to help with anything when it comes to cars or sidejobs after having him linked back to a rear end collsion with my 2001 escort in 2017 leaving me with a broken neck snapped arm and spine tore in half.

Is there anyway to check the heater circuit is the two brown wires on the one side or the two other colored wires at the o2 sensor to see if its good? I see its suppose to supply 12 volts from o2 harness connector with key on is that at all times the heater circuit will have 12 volts or will it cycle on/off 12 volts?
Now to check the o2s you had told me to test which to wires at the o2 sensor for 450mv or ohm resistance or continuity resistor or is it the mv setting on the ohmmeter? Both threw codes for the heater circuits and bank 2 sensor 1 has insufficent activity sometimes. I can reset the codes halfway thru the trip and didnt come back in 40s degree weather but few nights before reset thru dic driving the service engine light popped back up with same codes while driving. Never had the insuffienct code so i bet the o2 sensors are on there way out. Ive driven the car 1500 miles since ive had it was making repairs and usually baby throttle it had just headers. After the cam swap and dyntotune run it up to 5k-6k rpms 10 times on dyno for tuning purposes and ice since floored the throttle as well.

Maybe the o2s are on their way out appear to be original. I deleted the rears when i did headers last june and only had p0140 p0160 for rear o2s as well as p0410 occassionaly for air pump but i got those turned off with the dyno tune 2 weeks ago.

So what im asking again the two brown wires are heater circuit or the other 2 and is it a constant 12 volts supplied to heater circuit and for the o2 to test good 450mv is what i had tested last time but since having it tuned and ran hard o2s may be on there way out. I have 2 spare used delphi and which two wires am i testing for 450mv and is there anyway to test the heater circuit part of the sensor with an ohmmeter? I may try heating them up if i can find a torch.

 

What ended up being your problem with the o2 o2s?

 

To check the O2 sensors you will need to take an ohm reading…the same colored wire are for the heater and should measure 3.5-14 ohms (I measured 5 ohms)…the other 2 wires are for the O2 signal circuit…on a cold sensor you should see OL or 0 or whatever your ohm meter reads when the leads are not connected…mine shows arrows as in the picture.To check the harness side of the circuit from the connector to the PCM it’s easiest to use a scan tool…remove the OXY SEN fuse and with key on all O2 should read the 450mv bias voltage on the scan tool…I’ve checked my B1S1 voltage with a voltmeter on the harness side and I read 5.0 volts on the low ref wire (tan/white) and around 4.60 on the high ref (purple/white)…to measure the heater circuit on the harness side you should see 12 volts on the brown wire key on and ground on the black wire…you can just take your voltmeter and connect both wires to your voltmeter and you should see that same 12 volts…last month I had a B1S1 low activity and my O2 was stuck at 100mv and my fuel trims were pegged full rich because the PCM was reading a lean condition…since I was changing one I decided to change all 4…ordered 4 Delphi O2’s from Rock Auto and the upstream did not work…sent all 4 back and went to NAPA and ordered 4 Bosch…went through 3 sets of upstreams that didn’t work took them back and decided on Denso’s from Auto Zone…they worked fine !!

 

Ok i got 13ohm went up to 14 15 but stayed at 13 for the heater circuit on both delphi o2s. These are spare rear 04 ls1 o2 sensors i have laying around. I havent had a chance to check the ones on the car think theyre original with 92k. Ill check both the o2 signal wires for 5 volts and heater circuit at harness for 12 volts but does the fuse have to be unplugged for it to read the 5 volts or is that a constant key on as well as 12volt heater circuit and what fuse is it or is that for the 450mv reading at the o2 plug signal wires you are saying the fuse has to be pulled? Yes the signal wires both stayed OL as if they werent making contact or mentioned but heater circuit check out fine. I dont have a torch or id heat these up to see if i get 1 volt. These maybe good ones used on a bone stock 04 gto tho i think its time for some new afs75 or denso to get the car tuned up. I didnt start having this front o2 problem till having the car dynotuned to 6k rpms. It was ran hard and since ive started driving it somewhat hard. Probably does need new o2s to keep up.
Heres what i got nice snap on i dont have a live data o2 reader to see the current o2 readings. Heres what the fluke 77 says. How much was your snap on scan tool or is that just an ohm meter? This innova scan tool reads live o2 data half the price of the other tools.

 

This 35$ tool would appear to read live bank or stfs data ? Would be handy if it was accurate and durable. I had a actron scantron from advance auto parts for 100$ would read live date temps, map, timing, fuel pressure on ford vehicles equipped with fuel rail pressure sensors but not sure if this tool is durable or accurate as the others.

The codes i get are both p0135 p0154 p0155 for both heater circuits and insufficient activity on one of the sensors. I dont have low voltage or lean codes.These codes didnt show up till having it dynotuned just the one heater circuit code and reset came back again few days later in 40 degree weather with both heater circuit codes and one insufficient activity. I think the sensors are bad. I may get a chance to swap these delphi sensors and check the new o2 extension harnesses for 5v signals and 12 volt heater circuit. Its not a constant issue but pops up randomly on 20-30 mile trips reset and either come right back or dont come back.
Would amazon or rock auto be a good place to get the AFS75 or denso o2 sensors since autozone is twice the price.

 

Sorry didnt see u asked ?. Mine was the heater. When heated only went to 450omhs. Ur in the wrong range. U need mil ohms.

 

Key ON engine OFF to read the 12 volts for heater circuit power and for the 5 volt bias voltage...the 450mv is what you'll see with a scan tool if you had one...ONLY if you had a scan tool would you remove the O2 heater fuse because when the key is turned on that 450mv will drop to below 200mv's after a minute or so.

 

I don’t know if Rock Auto sells Denso !!..you would have to look.

 

i put the rear o2 sensors from an 04 gto they measured like yours on the snap on tool delphi 4 ohm or whatever with the same fluke 77. One o2 harness had melted the loom but the wires werent melted i tucked them up away better on the passenger side. Both read 4.9 volts 4.5 volts for the o2 signal wires on each side and 12 volts for the heater circuits. The original AFS measured 13-14 and the flat style rear o2 delphi measured 4ohm like yours in the above pictures. They're within range of what you told me. Ive done this before purchased rear o2 bosch new each for 42$ from napa for ls1 corvette that had 24" wires to put on a 98 z28 with headers instead of extension harnesses. Everything is good from o2 circuit 4.5-4.9 volts on signal wires and 12 volts on heater circuits. Would you happen to know which is a better o2 sensors the original AFS that measure 13-14 or the delphi that read 4ohms.

 

well i changed the o2s to some delphi flat style connector off an 04 gto rear o2s with 114k miles the car ran good first start with o2s but yesterday on a long spirited city drive ran kind of rough and managed to throw p0154 for unsufficient activity and heater circuit. The orginal are afs 14ohm and these are delphi 4ohm. Im not sure if its because i disconnected the battery at the same time it did manage to throw iat high voltage codes which it first did after a cam swap and soon didn't have those codes. I tested iat sensor with another and tested the same range. It would need to be revved at start or die stahl out but would stay running once in gear.

I may look into a new set of the afs75 someone told me denso were the best o2s.

 

Hi C5 Diag,
I hate to bump an old post but I'm currently chasing a p0153 (b2s1 o2 slow to respond) code on my C5Z that I've had intermittently since doing LT headers. I bought a denso o2 sensor off of eBay that was dead, a bosch o2 sensor off of eBay that was also dead, and finally got a denso from AutoZone that seems to work and report voltage changes on my obd2 scanner. My question is, when monitoring the B1S1 and B2S1 voltage when I turn the ignition to on while the engine is off, the b1s1 sensor (which I believe is original and was never changed) drops slowly to around 200mV, HOWEVER the new b2s1 o2 voltage goes all the way to zero. Is that an indication that the harness isn't heating the o2 properly? I checked the fuse and it looks fine visually. Thanks for any help!

 

Yes, if you were to remove the O2 heater fuse and with key ON you would see a bias voltage of 450mv…now install the fuse and you should see the voltage drop from 450 to well below 200 the longer you leave the key on…if you see that the heater circuit is functioning !!…as far as the code with LT headers the O2 sensor is much further aft from where it was with a stock exhaust manifold…the PCM is looking for the time the O2 sensor switches from lean to rich and then rich to lean and if too slow will set an 0153…that switching time is because of where the O2 sensor is with those long tubes…most owners with this issues get the car tuned to alleviate this.