Heated Oxygen Sensor

[mkvapil]

Ok, my 2003 Jeep GC Limitied 4.0 engine light came on again and this time the code is P 0031, which is 02 Sensor Heater Control Circuit Low (Bank 1 Sensor 1).

Where is Bank 1 Sensor 1?? So I can replace it myself. Should I replace the oxygen sensor in other bank? Thanks in advance.

[pkucan]

I hope to find this out too. What I can tell you is that on FLM's that have eight cylinders Bank 1 is on the side with the number 1 plug. Sensor 1 is upstream or before the cat convertor. Bank 2 is on the side with the number two plug and sensor 2 is downstream or after the cat convertor. I haven't been under my 98 4.0 JGC but will when the weather warms up.

Forgot to add ( the other sensor) If it ain't broke don't fix it.

[mkvapil]

now what??? After replacing the oxygen sensor with a Bosch brand.....now i am getting a new error code....P 0135.....Heated Oxygen Sensor Bank 1 Sensor 1 malfunction. What's the deal?

[pkucan]

Have you erased the previous code before replacing the sensor? Erase the 0135 and see if it reappears.

[mkvapil]

yup. code P0135 wasn't there before i changed the sensor. It was just P0031 and then changed the sensor. Unhooked the battery to clear the code. Now its saying P0031 and p0135

[Bob D.]

Originally Posted by mkvapil

yup. code P0135 wasn't there before i changed the sensor. It was just P0031 and then changed the sensor. Unhooked the battery to clear the code. Now its saying P0031 and p0135

There have been a lot of complaints about after market 02 sensors, especially Bosch, when used on newer Jeeps.

The P0135 Oxygen sensor heater element fault code could also be due to a short, open or high resistance in the wiring harness or harness connectors. Also check fuse # 16 in the under hood Power Distribution Center. (Although unlikely since one fuse is used by all 02 sensors I think and the code is only for one)

Here is a more detailed description about code P0135/Heated Oxygen Sensor:

The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The PCM tracks how long it takes for the oxygen sensor to begin switching. If the PCM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0135.

In simpler terms, the 02 heated circuit heats up the 02 sensor electrically rather than waiting for exhaust gasses to warm it up and allows the engine to transition from open loop (fixed, pre-programmed fuel mixture and other engine settings) and reach closed loop (variable engine settings) operation sooner. The after market sensors sometimes have a problem pre-heating the element properly. I'm willing to bet your Jeep runs fine after it reaches operating temperature, (but with possible reduced mpg if it's staying in the richer mixture, open loop mode) it's the open loop/closed loop transition where the PCM induces a fault code due to lack of or incorrect pre-heating.

I would first check all the wiring and fuses associated with the 02 sensor for continuity, if you still get the code return the Bosch sensor and replace it with an OEM sensor.

[pkucan]

Originally Posted by mkvapil

yup. code P0135 wasn't there before i changed the sensor. It was just P0031 and then changed the sensor. Unhooked the battery to clear the code. Now its saying P0031 and p0135

How much time must elapse with the battery disconnected before the codes are erased? This doesn't always work on Ford/Lincoln/Mercurys.

[mkvapil]

Originally Posted by pkucan

How much time must elapse with the battery disconnected before the codes are erased? This doesn't always work on Ford/Lincoln/Mercurys.

I waited like 5 minutes....

[mkvapil]

Originally Posted by Bob D.

There have been a lot of complaints about after market 02 sensors, especially Bosch, when used on newer Jeeps.

The P0135 Oxygen sensor heater element fault code could also be due to a short, open or high resistance in the wiring harness or harness connectors. Also check fuse # 16 in the under hood Power Distribution Center. (Although unlikely since one fuse is used by all 02 sensors I think and the code is only for one)

Here is a more detailed description about code P0135/Heated Oxygen Sensor:

The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The PCM tracks how long it takes for the oxygen sensor to begin switching. If the PCM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0135.

In simpler terms, the 02 heated circuit heats up the 02 sensor electrically rather than waiting for exhaust gasses to warm it up and allows the engine to transition from open loop (fixed, pre-programmed fuel mixture and other engine settings) and reach closed loop (variable engine settings) operation sooner. The after market sensors sometimes have a problem pre-heating the element properly. I'm willing to bet your Jeep runs fine after it reaches operating temperature, (but with possible reduced mpg if it's staying in the richer mixture, open loop mode) it's the open loop/closed loop transition where the PCM induces a fault code due to lack of or incorrect pre-heating.

I would first check all the wiring and fuses associated with the 02 sensor for continuity, if you still get the code return the Bosch sensor and replace it with an OEM sensor.

That is what I am afriad of.....I've read several topics about Jeep disliking Bosch brand oxygen sensors. I guess I will have to take it back to Advance Auto. But, where can I find an OEM parts for the Jeep? How about Denso? I will not go to Jeeps dealership for Mopar parts since they are usually way overpriced. Ebay would be my best choice, right?

Also, i will check the wiring and fuse.

[Bob D.]

Originally Posted by mkvapil

That is what I am afriad of.....I've read several topics about Jeep disliking Bosch brand oxygen sensors. I guess I will have to take it back to Advance Auto. But, where can I find an OEM parts for the Jeep? How about Denso? I will not go to Jeeps dealership for Mopar parts since they are usually way overpriced. Ebay would be my best choice, right?

Also, i will check the wiring and fuse.

I wouldn't buy one from Ebay, why risk more headaches?
If the electrical circuit checks out I suggest just buying one from the dealership, they're only a few bucks more and discounted if you buy online.

[mkvapil]

they don't make the same oxygen sensor anymore so I ordered a Denso brand.

[mkvapil]

Got my new Denso heated oxygen sensor from rockauto.com to replace the Bosch brand.....but dang connector didn't fit and the wires are too short. How can they send me a part which they say will fit my Jeep? I put the old heated sensor back in and erased the codes. Now only one code comes up....P 0031. Back to square one.

Do not get Bosch for the Jeep! Jeep hates Bosch!

Now I need to find the right Denso part or maybe an AC Delco heated sensor?

[reekor]

Denso or NGK will work. Bosch is a no no in Chryslers. So why not extend the wires and use the connector from the old one?????

[mkvapil]

Doesn't cutting the wires and using the connectors affect the PCM?

[reekor]

No.

Originally Posted by mkvapil

Doesn't cutting the wires and using the connectors affect the PCM?