P0141 code. Replaced sensor still getting SES

andrewwynn · #1 02-03-2018, 10:15 PM

I started getting a 0141 code (bank 1 sensor 2 O2 sensor heater circuit).

Only happened when ambient was cold. Reset CEL and it would stay off for a day or two.

Replaced the 1-2 sensor but before replacing I measured the Ω on the heater and it read normal so I also measured the voltage on the heater when starting and it started about 9.5v and climbed to 12. The 2-2 sensor behaved the same way.

Since I already had the momentum I changed the 1-2 sensor and no error for a day or two but then it came back and now it trips every cold start.

I thought I read that interaction with 1-1 sensor or SAP can cause the error.

I haven't either measured actual current draw (have to cut the wire to do so) or swapped the banks to see if the error would move (to determine if I bought a bum part).

I get voltage on the heater circuit, I get normal looking values from all four sensors though 2-2 reads consistently lower so I'm thinking of replacing that one to make them more similar.

Confirming does anybody know for certain that bank 1 sensor 2 is the outboard (starboard) side? Maybe I changed the wrong one.

I don't want to shoot a parts cannon at what should be a simple fix. I don't know where the other end of the wire comes from there might be a short from a previous oil leak does anybody have experience with this situation?

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80stech · #2 02-04-2018, 01:35 AM

Are you measuring voltage across the heater element? or referencing ground or supply? According to the wiring diagram the DME grounds the heating element. If you disconnect the sensor long enough to generate a sensor code you could verify if you are working on the right one.

andrewwynn · #3 02-04-2018, 04:00 AM

Measured voltage across element im pretty sure that's how it's possible that the voltage varies from 9.5 to 12v unless PWM is ramping up the RMS voltage to soften the impact on the heater element. I didn't run a continuous test just a couple minutes to confirm they both (post cat) lit up. I was in an enclosed garage I couldn't keep the motor running.

I can real time work see all four sensor values so I can instantly confirm which sensor thanks for the suggestion.

I "had a bad feeling" about the sensor not being the cause when I measured the Ω and it seemed inline with what was expected.

I'm hoping for a fouled connector (doused with oil for example). The "official word" is if not the sensor or wiring it's the brain.

80stech · #4 02-04-2018, 04:48 AM

If you are getting power to the heating element that almost rules out a wiring problem because the DME can only set a code from what it sees internally. Will be interesting to see if the 9.5 volts was enough of a problem to set a code.

andrewwynn · #5 02-04-2018, 05:02 AM

The 9.5 lasted seconds.

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80stech · #6 02-04-2018, 02:09 PM

Do you have DIS ? It might be intersting to see where that code takes you up the diagnostic tree.

upallnight · #7 02-05-2018, 12:19 AM

A sensor 2 will be a post cat sensor. If it is a heater circuit either the circuit is opened or you don't have power to the heater. Easy enough to check.

andrewwynn · #8 02-05-2018, 04:08 AM

I measured voltage on the heater at start up I don't know how long it stays on

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80stech · #9 02-14-2018, 12:23 AM

Did you get anywhere on this?

andrewwynn · #10 02-14-2018, 09:08 AM

Oh thanks for posting. Made possible headway. I put all four sensors into my real-time feed on my dashCmd app and noticed that the new v. old Post cat sensor though each were relatively stable they were. Quite a bit different in value. I've read somewhere that the computer decided what to do with the heaters in concert with each other but I couldn't find out which way (bank or post/pre cat). Then after about a week of resetting my see every start, the post cat heater warning kicked in for the other bank as well. I had already decided to replace the other post cat sensor. When I measured voltage on the heaters they both showed power and they both showed resistance making it very difficult to figure out what's going on.

I'm ordering a new bank 2 post cat today and crossing my fingers the write up I found early on was correct about there being a programmatic link between the heaters. I will post the outcome.

To be clear: power at both heaters yet I still get the heater taking too long error.

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