Hi!

i have the codes p0031 p0037 p0051 and p0057 on my jku 2008 and there is no voltage sent to the o2 heater circuit. Key on engine off I get nothing, engine on I get like 0.1 volt.

does this mean my PCM is bad? I get the codes right away when turning the key to on position after I clear them.

 

Wiring going bad is unusual but sometimes the grounding is a problem. You may want to make sure all the grounds are clean and tight. Have you changed the sensor to make sure it isn't the sensor?

 

I have checked all the grounds and tried to unplug the sensors one by one, clearing the codes in between but still get the same codes undependent of which sensor I still have connected.

 

Have you replaced one of the sensors to see if that is the problem?

 

No I havn't. The NGK sensors seems to be hard to find here in Sweden. Ordered 2 of them but no one has them in stock.

One thing I found out now is that if I remove the ground for the heater circtuis (G104), the PCM sends out 12V to all the circuits when none of the are connected. If I connect one, it drops down to 0.95V. Does that give any hints?

 

Now you know the PCM is good. It still points to the sensor. I must not have this right, but it looks like you have a 2020 Jeep. It would be odd to have this problem especially on both sensors with a new jeep and this should be covered under warranty. What is the year of your jeep?

 

but shouldn’t it always send 12v to all the sensors? It does’nt matter wich one I connect, but when I do it drops to 0.95 volts. It’s a 2008 JKU

 

Not 100% sure on Jeep but the heaters in my Chev 02 sensors are 5V but I agree with Ron and Janet here in his post. Have you removed the plug at all sensors and checked the voltage on the heater circuit? You will need a wiring diagram to get the color codes for which wires are heater circuit. If you get full voltage then plug one in and see what it is and do for all 4. You could have a shorted heater and it is pulling the voltage down but not drawing enough current to blow the fuse. Also you could have a shorted supply with a wire insulation burnt through.

 

all troubleshooting I’ve read about for the wranglers sensors says 12v on the sensors heater circuits. All plugs are disconnected and the voltage I get from the PCM is 12v on all sensors. But when I connect any of them, all sensors gets around 0.95v, even the connected one. Apparently I Will get a new sensor tomorrow so will try that to ser of it does any difference, otherwise I Will get a new PCM later this/next week.

 

Hey Daniel--I know your post was a while back but I'm wondering if you found a fix (if a new PCM brought your voltage up to 12v on all sensors). I'm having the same issue. I'm not seeing any voltage on the HEATER CIRCUIT and have confirmed that the wiring from the PCM is good and that the GROUND at G104 is good.

I have a 2007 JK X. I'll take all the help I can get!! thanks yall!