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Chasing 0352 and 0358 codes on a 012 Boss

30
16
Exp. Type
HPDE
Exp. Level
Under 3 Years
Pittsburgh PA
After fixing my O2 sensor code issue (short in the harness) at the beginning of this season, I thought I would be good to go with no more electronic issues with my 5000 mile Boss. FYI, last year I replaced the crank sensor with one with the “extra” o-ring.

After 4 TNiA’s and a HPDE in 2021, I’m plagued with 0352 and 0358 codes. At the last TNiA, the car went in to what I would call 25 % power mode in the 2nd season. After resetting the check engine light, my 3rd session went great, but was in low power mode for the ride home.

The first of my 1 yr old MSD coils that I pulled a week ago had a dark spot on it, so I replaced it with one new Ford coil. I also replaced all 8 plugs today. I got another 0358 afterwards.

I noticed that I had 2 additional coils with a dark spot on it. I just ordered 2 new Ford coils and should get them mid week.

Just curious if anyone had similar issues and if the coils were the culprit. If so, are there any coil manufacturers that are better/longer lasting?

Thanks!

5DA033C7-D98C-4CFD-B55D-58D81F0531F1.jpeg
 
Seeing only 5000 miles on the car makes me think it's odd for electrical parts to be failing. Maybe something loosened up during the HPDEs and in the right conditions intermittently moves enough to break connectivity. What about the connections to the pcm or another short somewhere. Just and idea. Connections have given me goofy troubles over the years. I had an svt focus years ago that had a hid light that would go out at times that drove me nuts. Checked everything and could find nothing wrong - regular connections ok, light ok, loom ok..... Eventually I pulled the ballist apart and tightened all of the tiny pin connections which fixed the problem. I remember a video that went through the steps on diagnosing those codes - Sorry I can find it . Maybe you'll have better luck searching.
 
30
16
Exp. Type
HPDE
Exp. Level
Under 3 Years
Pittsburgh PA
Thanks, folks. I’m gonna replace the 2 coils with the dark spots with new FoMoCo coils. If that doesn’t work, I’ll follow the circuit and check for shorts/open circuits.
 
745
352
Your codes indicate an issue with the coils from the #2 and #8 cylinders. If the coils with the dark spots are not from 2 and 8, you need to replace those also.
 
30
16
Exp. Type
HPDE
Exp. Level
Under 3 Years
Pittsburgh PA
Your codes indicate an issue with the coils from the #2 and #8 cylinders. If the coils with the dark spots are not from 2 and 8, you need to replace those also.
Thanks for the post and thank you for making me aware that the last digit of the code is the cylinder #. I did not know that.
 
30
16
Exp. Type
HPDE
Exp. Level
Under 3 Years
Pittsburgh PA
After replacing the #2 and #8 coils, I haven’t had an 035X code after two TNiA’s.

I thought I was out of the code zone until a P0420 Cat Effìciency Below Threshold popped up today on the way home from Pitt Race’s last TNiA in 2021.

#%*&!

Anyone have any experience with P0420’s?
 
Last edited:

TMSBOSS

Spending my pension on car parts and track fees.
6,225
3,211
Exp. Type
HPDE
Exp. Level
5-10 Years
Illinois
No Worries. They are fairly easy to get to and remove. I did buy a socket made for the job and it made the swap easier. I first sensors I changed were under warranty. That ship has sailed. lol

Hope this fixes your problem.
 
30
16
Exp. Type
HPDE
Exp. Level
Under 3 Years
Pittsburgh PA
No Worries. They are fairly easy to get to and remove. I did buy a socket made for the job and it made the swap easier. I first sensors I changed were under warranty. That ship has sailed. lol

Hope this fixes your problem.
I was getting an O2 sensor code last year at this time and swapped out the Bank 1 downstream O2 sensor before I found the short in the wiring harness.

7 track events on that O2 sensor. I guess I’ll buy spare O2 sensors in addition to the spare coils I have in my spares kit.

Thanks, again.
 
14
37
Exp. Type
W2W Racing
Exp. Level
Under 3 Years
Lawton, OK
Thanks, folks. I’m gonna replace the 2 coils with the dark spots with new FoMoCo coils. If that doesn’t work, I’ll follow the circuit and check for shorts/open circuits.
Did you use dielectric grease on the coils when you installed them? Just asking because I haven't seen anyone mention it.
 
I had a P0420 code and it was the bank 1 catalytic converter. This was 2016 and 24k miles. It was covered under emissions warranty. Cost 397.61. Good luck.
 
Do you know what the failure mode was in case the O2 sensor replacement doesn’t work?

Was the catalyst blown out?
No I don't. The code says Catalyst System Efficiency Below Threshold (bank 1).I had good dealer at the time and they did all the troubleshooting. I don't have a scan tool so I don't chase codes. I know just enough to know what I don't know. Good luck
 
30
16
Exp. Type
HPDE
Exp. Level
Under 3 Years
Pittsburgh PA
BTW, I replaced my 7 track event old downstream O2 sensor and I was good to go today after four 25 minute track sessions. No more P0420 codes.

I did get a PO300 random misfire code on the 3rd and 4th session, but it wouldn’t be a track day without a code. 😆

Reset it and forget it.
 

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