Check Engine light on
I have a customer that just got back from the dealer where they installed a new aftermarket (Direct Fit) Walker o2 (b1S2) sensor. (OEM sensor availability is about 2 weeks away) The following image shows what the dealer found when the vehicle arrived in their service department. The vehicle was in another service center and they wired in an aftermarket (universal fit) unit that was apparently miswired and caused a no start condition.
The following DTC's were stored in the vehicle:
P0141 - O2 Sensor Heater Circuit B1S2
P0136 - O2 Sensor Signal Circuit B1S2
P0138 - O2 Sensor Circuit High Voltage
As I was checking my data on my scan tool, I noticed B1S2 voltage at 0.434 V. Check my voltage at heater control my reading were 12.4 volts and the ground was at 0 volts,
Checking the signal side volts to battery negative measured: 0.445 V.
Following the KIA recommended test (I know using an ohmmeter is not the best) I checked the sensor signal return back to the PCM and ground and found an open with a spec of 1 ohm.
So I was not sure if I was correct on my testing I decided to supply a ground on the signal return and sampled another reading at the scan-tool which measured 0.734 V with a nice sweep. (screenshot from the attached Snapon Shop-stream file)
I posted an attachment showing this also a snap throttle acceleration showing a volt change of the signal as it was grounded.
[NOTE: The above has been edited for clarity]
we suspect that the heater circuit was incorrectly wired and may have caused the open in the ground circuit within the PCM. What are your thoughts?
Before replacing the PCM we want to make sure that we are doing so with the highest confidence.
And again guys sorry for the missing communication.
The diagram you have shows the heater circuit to be controlled by the pcm grounding it to turn it on. I would start by installing an OE sensor and get rid of the universal crap.
Hello Dave Thanks for the input Dave i was thinking the same, i failed to mention that the universal sensor that you see in the picture was replace by the dealership, for some reason they install the aftermarket walker instead of a OEM could you explain how i would check the ground side of the heater circuit.... and again thanks for the input...
The ground side can be checked by connecting a load such as a light bulb between the heater power feed and the pcm ground circuit. It should light when the circuit is grounded. It may stay on solid or flash depending on design. You may be able to command it on with scanner bi-directional function.
'Dave i did check the ground side with my volt meter and had -12.4 volts with key on engine off so turn of the ignition and had 0 volts don't know if that was a suitable test or not and my heater resistance was 14 ohms to 16 ohms
After clearing the codes, on start up, the PCM will quickly measure the aftermarket 02 heater amperage draw and if the amps are too high or too low, the PCM will stop grounding the 02 heater coil. Some 02 heater coils measure 12 ohms in resistance but the KIA OEM 02 heater coil may have a different resistance.
Hello Ray I measure 14 to 16 ohms on a hot 02
You only have a quick second to check the ground control on the heater circuit. As soon as pcm detects and issue, it will stop grounding that 02 heater. Do like the others have said and put a test light across the power and ground control, clear codes, start engine and watch for the light to either flicker or stay on. If the vehicle did not start after the wires were damaged, and there is no…
Ok saifullah I understand now what Dave was telling me about load test I will test and post my results
>watch for the light to either flicker or stay on. As in PWM ? Power or ground ? From what I'm familiar with, there's a less than 30 second window, temperature and time dependent. Ya gotta be quick with test method and equipment set up to catch and observe.
Yes PWM. How am I supposed to know if he knows what pulse width modulation is?? According to the OEM schematic he provided, its ground side controlled.
Saifullah I lost my Down ground will post a diagram shorty, I don't believe its a heater circuit issue....
Load test all 02 sensor wiring from pcm to 02 sensor. And lets go from there. Make sure 02 sensor connector is not wet. And like darby said, make sure the pins are in the right spots
Customer will be back tomorrow afternoon will post my test results....
…gt;How am I supposed to know if he knows what pulse width modulation is?? Good question. I guess it wouldn't hurt to respectfully point to the theory of operation and the reasoning for the heater. Here's a link you could share: knowyourparts.com/technical-reso… This link is a little TMI, but interesting, to me :O)…
Hello Hollis Great refresher information, I would like to ask you on the control side of the sensor and ground but not talking about the heater side of the circuit, is the sensor ground pulse-width modulated, because it's noted as a down ground just wanted some input about that.
I don't think the sensor signal is grounded per se as is the PCM uses the current produced / flowing from it, to the PCM to which it converts to a representative voltage value on the scanner. If that's what you're asking. The heater circuit from my understanding is the only circuit that is grounded. The schematic indicates a ground supplied by the PCM, now if it's a shared ground or dedicated…
Hello Hollis Thanks for the reply but take a minute when you have time to explain the new update diagram I posted the one that show the down ground and explain that circuit I believe it's pin 41 Thanks again
Sorry, just got some time to look at this. I can't determine from the diagram if it's a PWM'd or constant ground . I'd have to test it on the car. You can do it with a test light that has an incandescent bulb. A PWM'd ground or power for this application is influenced by ECT and Time, engine running, so the frequency will be slower the warmer it is. From your other post, it seems you're…
Hello David I posted the pwm side of the circut around 9.4 volts and load tested the circuits it pulse for a few seconds then it went off. The duty cycle 0.9 then it jump to 99 How would I test the down side of signal ground. I measure the resistance didn't show a reading the specs says below one 1 ohm...
>How would I test the down side of signal ground. I'm not sure. I've been trying to explain it the best way I know how. Maybe we got our wires crossed, pardon the pun. Hopefully someone else can do a better job. Can you answer any of the questions I posed in my response above? I'm sure you'll figure it out. And in hindsight it will be something simple. :O)
>Pcm heater driver may be damaged Would you suspect if this is the case that it would code immediately ? I think it's within 5 seconds if I read the SI correctly.
Where did he say its sets or does not set immediately? You are giving me kia SI? Lol I have worked for kia/hyundai for over 10 years. Their "SI" is always "replace with known good" this is a super simple circuit. All that needs to be done is a load test on all the wiring going from pcm to the 02 sensor. There are even a few bypass tests (being the sensor) you can do and watch the scanner, but…
I was asking if you would think it would code immediately if the ground driver circuit for heater control was possibly fried. Leon just responded to my post above concerning I believe the sensor signal down ground , I'm not sure what he's asking or familiar with the term. I'm looking at the SI and now the clock, I gotta get ready for work. I think he has a sensor performance issue or trying to…
Had something very similar happen on a nissan altima - check to make sure the clocking of the wires are correct - they do not always put them where they should be, and 3 sensors I received were all clocked wrong for that particular vehicle - they were all bosch sensors too - make sure the voltages on the harness side match where they should go on the sensor side harness. the two white wires are…
Hello Darby Thanks much for your input, but unfortunately I didn't explain it right in my posting I fail to explain that the universal 02 sensor was replaced by the dealership and they installed a aftermarket O2 sensor brand name was walker sorry for the miscommunication there but should be posting my results on what fine soon Thanks again 👍
I think your 02 heater PWM volts and amps should look something like this on start up.
Hello Ray I will be doing more test this afternoon as soon as I get the vehicle back this afternoon. I will ask you to take a look at code P0136 I posted a new wiring diagram pin 41 what kind of ground is pin 41 I also posted a scope reading of my signal and ground it's not to get confused it's not the heater side circuit. Thanks again Ray
With your scanner, graph the rear 02 volts. Disconnect the rear 02, connect a regular test light to battery positive and touch the blue 02 signal wire terminal. The rear 02 volts should go from 0v to over .9v Or while driving the car at WOT, graph the rear 02 and the voltage should be .9v, then release the throttle and the rear 02 voltage should go low.