P0038 Hyundai Code - HO2S 12 Heater Circuit High

Hi, I have a 2004 hyundai coupe 2.0 se which recently threw a po139 error code. We read the code and assessed if it was a major worry and decided to reset/clear the code. After about a week the engine light reappeared and showed the same code. I had a new battery fitted and the light disappeared for another week or so and came back on. Eventually the car was booked in for other work (cambelt kit) and we replaced the rear O2 sensor. The light went off then reappeared the next day and has now thrown two new codes. Po 038 and po 137. I have read the blurb on what the possible cause (s) could be but am reluctant to keep fitting sensors at cost without proper diagnosis. The mechanic suggests that since the rear sensor has been replaced the older front sensor may be showing imbalance or voltage irregularity. It's not my field of expertise but I'm of the opinion that there is a different problem that no amount of sensor replacement will cure. Any help from somebody who has knowledge of this system would be greatly appreciated as I'm not about to keep chucking sensors at it fruitlessly.

P0139 code is for the Rear O2 sensor Bank 1, the other two codes are for the same sensor (some sensor have many codes for different problems). In my opinion, either the sensor he replaced is not the correct one or it was damage (which is a very common problem). By looking a the codes I can say that the first code was a normal old sensor code "Slow Response" typical for old sensor. The two new codes (Low voltage, Circuit High ) means that the sensor is either disconnected or bad.

P0139 Hyundai - HO2S Circuit Slow Response Bank 1 Sensor 2
Read more: https://www.autocodes.com/p01...

P0137 Hyundai - O2 Sensor Circuit Low Voltage Bank 1 Sensor 2
Read more: https://www.autocodes.com/p01...

P0038 Hyundai - HO2S 12 Heater Circuit High
Read more: https://www.autocodes.com/p00...

Yes that's what I understood from what I read before about the rear sensor showing a slow response, I was advised by others to replace the sensor and the mechanic commented that it looked like it's life was over, not knowing if they can be tested I went ahead and replaced it. Now it is throwing the new codes I'm reluctant to replace the front heat sensor which one of the codes points to until I have a lot more knowledge of what's really happening.

No, it's not for the front sensor, it's for the same sensor. All codes are for the same sensor. Have your mechanic warranty the sensor or maybe he didn't connect the sensor. Do Not Replace the Front Sensor.

Actually scrub what I just said about one of the new codes pointing to the front sensor I just checked the pic I took from the code reader and it does indeed refer to the rear sensor 2. More investigation is needed to check the fitting etc I feel.

Thanks Yes I just realised I was reading the code msg wrong and corrected myself above lol Yea so it may pay me to get and take a look to see if the plug is in right to start and if it is pay another visit to the garage to point out the problem is still in the same sensor.

Ps thanks for help so far! I will update the outcome when I have got a bit further.

Ok so heres the update on the issue. I had the car taken back in and pointed out that the codes were all still relevant to the second sensor and required further investigation so the guy ordered another sensor from the same supplier but of a different type and removed the one he had previously fitted. The one previously fitted was apparently dead and he originally suspected burnt out which was worrying to hear at first.however he did say that they can be very finicky straight out the box and even damaged quite easily as they apparently are quite fragile and so even a drop on the floor may render it useless while still in the packet. Whats even more worrying is that if they are quite fragile why are they not protected a bit better ie with bubble wrap inside the box? The new sensor was fitted and the codes erased from the system and i drove the car a few miles initially to see if the light popped on again (it came on within two miles after the first sensor was fitted) and hey presto it stayed off. Now over a week later and some 300 more miles on the clock its stayed off and is running fine. Fingers crossed thats the end of that little episode. Many thanks for the pointers and advice i have recieved from here it has been an invaluable aid. Just for the record i believe the sensor fitted now is a corbiere.

Thank you for letting us know. I'm glad the problem was fixed.

hi I have an '06 elantra and the code P0038 P0136 came up and that was the O2 sensor which sensor is it that needs replacing, the up stream or down stream sensor? and where is the best place to get it at the most cost efficient price?

Both codes are for the rear sensor (down stream). Most auto parts offer competitive prices for aftermarket sensors.