I have the code p0139. replaced o2 twice, need to track down the wiring. does anyone have some advice? my cat fell off and that is what damaged the 02/wireing. Se 4 door motel 2.4 dohc 149cl

No code tells you to replace a part , need to do diagnostic's for said code .
P0141 - O2 Heater Circuit (Bank 1, Sensor 2) Description: See the description for DTC P0135. Possible Causes: See the possible causes for DTC P0135. Diagnostic Aids: See the diagnostic aids for DTC P0135. Application Key On Engine Off Key On Engine Running Continuous Memory All GO to Pinpoint Test DW .
DW: Heated Oxygen Sensor (HO2S) DW: Introduction DW1 CHECK FOR DIAGNOSTIC TROUBLE CODES (DTCS) Are DTCs P0040, P0041, P0053, P0054, P0055, P0059, P0060, P0132, P0133, P0135, P0138, P0139, P0141, P0144, P0147, P0152, P0153, P0155, P0158, P0159, P0161, or P1127 present?
Yes No For DTCs P0040 or P0041, GO to DW2 .

For DTCs P0053, P0054, P0055, P0059 or P0060, GO to DW14 .

For DTCs P0132, P0138, P0144, P0152 or P0158, GO to DW20 .

For DTCs P0133 or P0153, GO to DW3 .

For DTCs P0135, P0139, P0141, P0147, P0155, P0159 or P0161, GO to DW9 .

For DTC P1127, GO to DW19 . For all others, GO to Section 4, Diagnostic Trouble Code (DTC) Charts and Descriptions .
DW9 DTCS P0135, P0139, P0141, P0147, P0155, P0159 OR P0161: CHECK FOR A SOURCE OF POTENTIAL HO2S CONTAMINATION

• Investigate the following items as potential sources of HO2S contamination:
  • use of unapproved silicon sealers
  • fuel contaminated by silicon additives
  • excessive oil consumption
  • glycol leaking internally in the engine
  • lead-contaminated fuel
  • short drive cycles in cold weather
  • use of unapproved cleaning agents

Is a concern present?
Yes No REPAIR the source of the contamination.

CHANGE the engine oil and oil filter.

RESET the keep alive memory (KAM). REFER to Section 2, Resetting The Keep Alive Memory (KAM) .

REPEAT the self-test. GO to DW10 .

code p 0139 refers to heated oxygen sensor (HO2S) 2 bank 1--slow response===causes --heating inoperative--wiring--HO2S
or
oxygen sensor(O2) 2 bank 1---slow response===causes--wiring ---O2 sensor
as you have replaced the O2 sensor twice with no results then it will be the heated sensor that is faulty
heated sensors are the units in the exhaust manifold of exhaust pipe before the cat converter and O2 sensors are the units after the cat converter
It is normally the HO2 sensor that fails and the wiring problem is from not using the correct special socket for installation or removal that causes damage to the fragile wires to the unit

Probably replaced a good sensor. This codes could be from a bad sensor, a vacuum leak, or an exhaust leak before the sensor.

Causes
A code P0139 may mean that one or more of the following has happened: The oxygen sensor is faulty The wiring to the sensor is broken / frayed There is an exhaust leak


Possible Solutions

The simplest thing to do is to reset the code and see if it comes back.

If the code comes back, the problem is more than likely the rear driver's side oxygen sensor. You will likely wind up replacing it but you should also consider these possible solutions:

Check and fix any exhaust leaks
Check for wiring problems (shorted, frayed wires)
Check the frequency and amplitude of the oxygen sensor (advanced)
Check for a deteriorating / contaminated oxygen sensor, replace if necessary Check for inlet air leaks
Check the MAF sensor for proper operation

main problem that you have not addressed with the o2 sensor is the fact that the wires have been damaged and that there is a dead short to ground. Probably the wires are severely twisted and a wire has broken and touching the earth wire or the metal body of the sensor.

Ok i see you replaced your cats Now the question is did you use oem parts ?? Cause that can make all the difference! And do you have dual cats if so did you replace the one twice or both ?? Also check your ground wire for corrosion or a loose connection this ground can be found either on the right front of the engine or the rear of the engine. one more thing just make sure there are no leaks before the converters. Good luck

2003 cavaleir with code po141. this codes is saying o2 heater , so yes if sensor wiring is good then o2 is bad, but which o2 did you change? the correct o2 is the rear one after the converter not before the coverter, theres one up by the engine and i think its on the exhaust manifold and then another o2 down on the exhaust after the cat, thats the one you need to replace, let me know is thats the one, if not and you replaced the one at engine then replace the other one after the cat and this will solve the problem, let me know hope this is helpful.

I have about 15 years experience with Audi/VW. The coolant issue is more like the result of the ECM coolant temp sensor failure. The Cat code might be the front oxygen sensor on that bank and not the front cat. If you need more information about this repair please fell free to contact me at [email protected], I have over 30 years of automotive experience to assist you, thanks.

Hi Garcha,

Both codes relate to O2 Sensor # 2

Code P0139: O2 Sensor Circuit Slow Response - Bank 1, Sensor 2
Code P0140: O2 Sensor Circuit No Activity Detected - Bank 1, Sensor 2

A faulty O2 sensor will mean incorrect signals will be sent to the EFI computer, causing erratic engine running.


Cheers,


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Hi the code P0139 is Bank 1 sensor 2 lambda sensor fault ,possible wiring or sensor fault even if you replace the sensor you need to have the MIL lamp turned off by a Diagnostic machine,it is possible you have another fault such as poor Catalytic converter efficency giving the same fault code ,Would recomend you get the car checked and read the "live" data as the car see`s it to make an accurate diagnosis and cure