I've search but can not find the info I need.
I got this code O2 sensor Circuit high voltage( bank 1 sensor 2)
I have already replace the )2 sensor with Oem and this code is back.
Any clues as what to do next, and what does all that mean.
Thanks
Shawn

 

Check out http://www.gearchatter.com/viewtopic8898.php for some very detailed information on this fault.

 

What code number did it throw? P_____?

 

I'm sorry, I thought that I put that in my post.
It is a P0138

 

has anyone resolved this problem? mine keeps throwing this code about once a week. i dont relly understand the directions above.

 

do you have aftermarket exhaust or mods?

 

yes but i hav had them for a year and a half and this is the first time the code has been thrown. from what i am able to read, it seems that it is the rear 02 sensor behind the cat? part # 11780872674. its just wierd becuase the last thing i did was a crank pulley and new tensioner in july. no problems since then until the weather shifted here in tucson. idk i guess getting a new o2 sensor would be the first step?

 

Probably, but you would expect o2 sensors to last 50-75k(? at least.) How many miles on the front sensor? (I read once a rear sensor fault was triggered by a front sensor problem.) Each time you get the error, are you getting any other codes, too?

 

nope just that one sensor p0138. my car has just over 90k on it. so you think both sensors? the front one is way more expensive than the back. is there any way i can check them with a volt meter or my scan guage II? also the p0138 means a high voltage reading on the rear sensor?

 

which code here should i use

 

bump???

 

common guys no help?

 

Please report the freeze frame data from your scan tool ( the conditions under which the code was set).

The ECU checks for several things under the comprehensive component monitor of OBD-2.

P0138 means that the ECM detected a high voltage on the rear o2 of greater that approximately 1.4VDC for a period of more than 10 continuous seconds.

There are four wires on the o2 sensor. Two of them are the signal wires (can be identified by the gold pins in the male and female socket).

The other two wires are responsible for delivering a current / voltage to the heater portion of the o2. A cold sensor will not provide any output and the vehicle remains in open loop until the sensor reaches a minimum temperature of 600F.

The p0138 can be caused by the heater wires shorting out and delivering voltage intended for the heater to the sensor wires.

The ECU monitors for this condition continuously if the key is on; the car does not have to be running. If the condition is detected once a pending code is set, twice the SES light is lit.

There is also a possibility that the o2 could be providing a path internally from the heater circuit to the signal circuit.

Begin by looking at the value of the B1S2 on your scan tool with the car at idle, after a few minutes the voltage should be between .5 and .8 volts and fairly steady. If you find that the voltage is greater than 1 you are in luck because the problem is present giving an opportunity for further diagnosis.

If the voltage is too high, shut down the engine and unplug the second o2.
The voltage should be about .3 to .45vdc on the scan tool with the engine at idle and the sensor disconnected. (this step isolates the ECM as a possible cause of the high voltage and works for the front o2 as well).

If the voltage as described in the previous step is not in the correct range then check the connector and wires that go back to the ECM (look for the insulation melted together) as the problem is still present.

If the voltage is in the correct range after unplugging the rear sensor then replace the rear 02 sensor.

Check the front 02 sensor for aging: monitor the front o2 parameter on your scan tool (B1S1) and the short term fuel trim (STFT) parameter at the same time with the engine at idle.

The B1S1 should be out of phase with the STFT; both values should alternate high to low. If the STFT value exceeds a total of 8% peak to peak continuously then the sensor is slow and should be replaced; you will notice a smoother idle and response along with better mileage.

I hope this helps and please advise on how you make out.

 

awsome thank you so much, ill check all those out when i get a chance. Finals are coming up though and ive got alot of work on the plate right now. thanks again.
-J

 

so the stock sensors with the harness are like over $200, would something like this
http://cgi.ebay.com/ebaymotors/Parts-Accessories_Car-Truck-Parts-Accessories__OXYGEN-SENSOR-mini-COOPER-02-07-06-05-04-03-2002-2007_W0QQitemZ370141338306QQddnZPartsQ20Q26Q20Acce ssoriesQQadiZ2865QQddiZ2811QQadnZCarQ20Q26Q20Truck Q20PartsQ20Q26Q20AccessoriesQQcmdZViewItemQQptZMot ors_Car_Truck_Parts_Accessories?hash=item370141338 306&_trksid=p4506.c0.m245&_trkparms=72%3A727|65%3A 12|39%3A1|240%3A1318
work? i can do the soldering and wrap them in shrink wrap individually then cover with heat resistant wrap. What do you think?

 

Symptoms

There may be no noticeable symptoms except for MIL illumination. Possible high [FONT=Verdana,sans-serif][FONT=Verdana,sans-serif]fuel [/FONT][FONT=Verdana,sans-serif]pressure[/FONT][/FONT] can over rich the system.
Causes

A code P0138 may mean that one or more of the following has happened:

• Faulty O2 sensor
• Short to battery voltage in O2 sensor signal circuit
• High fuel pressure (not as likely)

Possible Solutions

Here are some potential solutions:

• Replace O2 sensor
• Repair short to battery voltage in o2 sensor signal circuit

 

thanks for the help. Im almost 100% sure its the o2 sensor, i was just asking if a sensor similar to the one aforementioned would work in my situation.
thank you again

 

The aftermarket sensor may work, however some people have not been happy with the results! Good luck and let us know how you make out.

 

Ok i checked again today. the rear sensor ranges from 86-130 im assuming this means .86-1.3 v. so i isolated the front sensor by disconnecting the rear and front never went over .91 v. i then plugged the rear sensor in and within 1 min it was up to 1.27 v. I checked the wiring on both sensors and the plugs and they seem fine. the rear sensor had a substantial amount of rust around the bung but no melted wires. So i found one here in Tucson for $170. anyone know where i can get one cheaper? Am i right about my asumptions and i have noticed the car idleing rough lately.
Thanks
-J

 

what about this one? its not Bosch but it should work?
http://www.rockauto.com/catalog/rafr...1387874k532105

 

What was the value on the scan tool for B1S2 (rear o2) while it was unplugged? ...........if it was in the range of .3-.45 the ECU is not the cause.

 

This is what i was going by, the stuff in the bold. Was i wrong?? It was steady holding at .4 but jumped right back up when i plugged it back in. I am still assuming you mean the B1S2 sensor may be the cause?

 

It appears that the o2 has failed internally!