P0157 trouble code help?

Tech discussions on the L77 6.0L V8.
CrashTestDummy
Posts: 1877
Joined: Sat Feb 07, 2015 8:31 pm
Location: Pearland, Texas

P0157 trouble code help?

Post by CrashTestDummy » Fri Feb 15, 2019 11:58 pm

I finally got a chance to get the car on the road the other day. About a mile in, the CEL comes on. I check the codes and it's a P0157! The car runs fine, otherwise. What I've done:

Solo Performance high-flow cats.
X-Force Varex exhaust system.

Note that the cats come with an O2 sensor extender to get the secondary O2 out of the exhaust flow a bit to make it think things are okay. I've also wired the fog lights per Steve's kit, which required pulling the under-hood fuse block to add some circuits. That's all I've done that I think could affect the O2 system.

What do I look for, or what do I test? Or am I screwed with the addition of the cats and exhaust?
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2010 Tahoe PPV (her car)
1995 DGGM Impala SS
1996 BBB Impala SS (11-second DD)
1985 Firebird - 310 LS1 C Prepared autocross car.
And some others
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Sanford
Posts: 87
Joined: Tue Dec 13, 2016 3:38 am
Location: Texas Gulf Coast

Re: P0157 trouble code help?

Post by Sanford » Sat Feb 16, 2019 1:15 am

Need to get ahold of a scan tool that reads data. Take a look at what the other bank is reading and see if the readings are close to each other or if there is a drastic difference.
The other method would be to swap the post cat sensor to the other bank and see if it sets a code for that bank.

David C.

CrashTestDummy
Posts: 1877
Joined: Sat Feb 07, 2015 8:31 pm
Location: Pearland, Texas

Re: P0157 trouble code help?

Post by CrashTestDummy » Sun Feb 17, 2019 9:44 pm

Finally got some time out in the garage. I hooked up the OBDII reader, I'm using OBDLink, and I'm seeing the O2 voltages for the Bank 1 Sensor 2 reading a solid 0.06v. It never changes. The Bank 2 Sensor 2, however, varies between 0.015 and 0.02v. The pre-cat sensors seem to be working okay.

Is my Bank1 Sensor2 dead?
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2010 Tahoe PPV (her car)
1995 DGGM Impala SS
1996 BBB Impala SS (11-second DD)
1985 Firebird - 310 LS1 C Prepared autocross car.
And some others
Do YOU have my SPID?

Sanford
Posts: 87
Joined: Tue Dec 13, 2016 3:38 am
Location: Texas Gulf Coast

Re: P0157 trouble code help?

Post by Sanford » Mon Feb 18, 2019 2:37 am

If the output of the sensor did not change from the time you started the car through the warm up time, it sounds like a dead sensor, unless you have a wiring/connection problem. I would just swap the after cat sensors and see if it readings follow the sensor. If the fixed reading moves to the other side, you have a dead sensor.

David C.

CrashTestDummy
Posts: 1877
Joined: Sat Feb 07, 2015 8:31 pm
Location: Pearland, Texas

Re: P0157 trouble code help?

Post by CrashTestDummy » Sun Mar 10, 2019 10:38 pm

Well, got that O2 sensor replaced. After running the car a bit, the CEL didn't turn off, and I was apparently not clearing it properly. The position 2 no. 2 sensor was showing about .01-.05 v while driving, I swapped the one I had just pulled off to the other side. It didn't seem to make much difference in the readings. I DID get the code cleared, and need to take the car out for a longer drive to see if it comes back on, but in the meantime, I'll get a replacement O2 sensor on it's way, just to be hopefully safe.

It WAS nice to be able to get out into the shop today, even though the humidity was so high the moisture condensed on the floor. :shock:
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2010 Tahoe PPV (her car)
1995 DGGM Impala SS
1996 BBB Impala SS (11-second DD)
1985 Firebird - 310 LS1 C Prepared autocross car.
And some others
Do YOU have my SPID?

CrashTestDummy
Posts: 1877
Joined: Sat Feb 07, 2015 8:31 pm
Location: Pearland, Texas

Re: P0157 trouble code help?

Post by CrashTestDummy » Mon Mar 18, 2019 3:36 am

Ended up replacing the other secondary sensor, just to be safe. Took the kids out for a drive with the ODB reader connected. It looked good, and we didn’t set the MIL off. I’ll drive it a few more times, then get it inspected. Fingers crossed.
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2010 Tahoe PPV (her car)
1995 DGGM Impala SS
1996 BBB Impala SS (11-second DD)
1985 Firebird - 310 LS1 C Prepared autocross car.
And some others
Do YOU have my SPID?

CrashTestDummy
Posts: 1877
Joined: Sat Feb 07, 2015 8:31 pm
Location: Pearland, Texas

Re: P0157 trouble code help?

Post by CrashTestDummy » Sat Mar 30, 2019 8:44 pm

So I figured we'd take the car to run some errands so we could get some miles and start cycles on it before taking it in for inspection. Since we seem to have some slow A/C leak, I recharged the A/C before leaving the house. About 1 mile down the road, the damn MIL comes on! When I get home, I check it, and the P0157 code has returned!!

This is with TWO brand new GM O2 sensors in the car!! I hooked OBDLink back up and ran it on the car in the driveway. Bank 1 Sensor 2 was reading a steady 0.05V, while Bank 2 Sensor 2 was reading about 0.03V, and that value did change a bit with a change in the throttle setting.

I AM running brand new Solo high flow cats, and they do supply O2 extenders, that bolt into the exhaust system between the exhaust and the O2 sensor, Could that be causing my issue?

The car ran perfectly for several months after installing the cats. The trouble seems to have started after installing the XForce cat back exhaust.

The connectors on both secondary O2 sensors look clean and are not bent. The wiring disappears up into the transmission tunnel, but look fine for what I can see.

Any ideas?
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2010 Tahoe PPV (her car)
1995 DGGM Impala SS
1996 BBB Impala SS (11-second DD)
1985 Firebird - 310 LS1 C Prepared autocross car.
And some others
Do YOU have my SPID?

s/c'd cav
Posts: 676
Joined: Mon May 30, 2016 8:12 am
Location: PHOENIX AZ

Re: P0157 trouble code help?

Post by s/c'd cav » Mon Apr 01, 2019 4:45 pm

the increased exhaust flow from the catback , mixed with the high flow cats , is what is causing the after cat o2's to freak out some

your best thing to do is get the car tuned , and have the after cat codes turned off

CrashTestDummy
Posts: 1877
Joined: Sat Feb 07, 2015 8:31 pm
Location: Pearland, Texas

Re: P0157 trouble code help?

Post by CrashTestDummy » Mon Apr 01, 2019 8:18 pm

I've thought of that, but am under pressure to get the thing inspected so we can renew the registration, which was up yesterday.

I may have found the problem, but need to drive it a bit to verify the MIL doesn't reset.
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2010 Tahoe PPV (her car)
1995 DGGM Impala SS
1996 BBB Impala SS (11-second DD)
1985 Firebird - 310 LS1 C Prepared autocross car.
And some others
Do YOU have my SPID?

lastcall190
Posts: 328
Joined: Mon Sep 11, 2017 10:17 am
Location: North Jersey

Re: P0157 trouble code help?

Post by lastcall190 » Mon Apr 01, 2019 8:23 pm

FWIW, making a code not report does not impact inspection/MIL status. Just hit a drive cycle after flashing the computer and you're set.

But if you figured it out to allow for inspection in its current form then great.

-J
2012 Caprice
!DOD : LS9 Cam : Pat G : Magnaflow : VCM

2008 CVPI
168k and going strong

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