Codes P0354, P0355 and P0357, check engine light?

Tiny
PETPARENT
  • MEMBER
  • 2004 MERCURY GRAND MARQUIS
  • 4.6L
  • V8
  • 2WD
  • AUTOMATIC
  • 247,250 MILES
Car has the codes P0354, P0355, and code P0357. Before it had P1336 and P0128 as well as 0355 and p0357. The car had blown out coil pack #4. I re-tapped cylinder 4 and put in a new plug spark plug insert and coil pack, also I put in a new thermostat because of code P0128. Because of the codes I had a mobile mechanic confirm my first code read.
Monday, January 27th, 2025 AT 2:33 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,068 POSTS
The codes you have are all related to ignition coils. Have you tried moving them around to see if the codes change? Are you experiencing misfires while the engine is running?

Also, confirm the PCM connectors are tight, clean, and dry. The PCM is located under the hood next to the power brake booster. See pic below

Let me know as much as you can.

Joe

See pic below.
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Monday, January 27th, 2025 AT 7:27 PM
Tiny
PETPARENT
  • MEMBER
  • 12 POSTS
What I meant to say is that the mobile mechanic relearned or reflash the computer in my car? Ignition coils are all new. You think that I should move them around before I try the new crank position sensor and?
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Tuesday, January 28th, 2025 AT 7:42 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,068 POSTS
Hi,

If all coils are replaced, I don't think that would be the issue. It could be related to the drivers in the PCM, but the only way to confirm is to perform diagnostics.

If you look below, I attached the diagnostics for P0354, 355, and 357. The codes all take me to diagnostics JF1 in the manual, which I attached below.

Take a look through them and let me know if you are comfortable performing them.

Take care,

Joe

See pics below.
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Wednesday, January 29th, 2025 AT 7:19 PM
Tiny
PETPARENT
  • MEMBER
  • 12 POSTS
Yes the answer was helpful. I will try the to diagnose the problem using your flow chart.
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Saturday, February 1st, 2025 AT 12:09 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,492 POSTS
Also, I would clear the codes, then start the engine for about 5 seconds and then run the codes again, this will give us the most relevant code to fix first, also, I would check the spark plugs, I have seen a spark plug get cracked and cause these codes.
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Tuesday, February 4th, 2025 AT 8:38 AM

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