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Discussion Starter · #1 ·
Recently my brother's caprice Wagon w/ 86k miles got a set of SLP shorties installed -jet-hot coated inside and out- as well as other work performed. He kept the stock cats. Herter tune w/ rear O2 codes disabled.

Since the install the car has had the P0154 code. Permanently. There was no code before the header swap w the original Sensor so they were left in. After install the code popped up after 30 miles, 2 brand new AC delcos were put in the front. Cured the problem for about 30 miles then came back (P0154). Drove around like that for a few months and now brought it back to the shop for a 3rd new AC delco 02 sensor that immediately repopped P0154. Almost guaranteed it isn't the sensor.

The transmission was previously R&R'd by someone very unprofessional. This was concurrent to the header swap. Damage occurred to the shift linkage, parts of the exhaust and the px solenoid ass'y. Could there have been damage to the O2 harness causing this P0154 ? Any tips on finding where the damage is? I can only see 2 causes for the P0154: damaged wiring between the 02 sensor and the PCM, or faulty PCM. I think I've ruled out damaged pcm by swapping in the stocker and still having the code.

The car is currently at my friend's shop. He changed the exhaust manifold gaskets to Earl's as the ones from the slp kit were leaking a bit. He also showed me the triangular gaskets that seal the headers to the cat converter. Both sides were completely disintegrated and blackened. They had essentially turned to soot. These gaskets were put on in Fall 09 with the headers. I've never seen them go that bad, especially not in so short a time. Any ideas what can cause these gaskets to go bad so fast ? A rich condition caused by the malfunctioning PCM (BOTH gaskets were shot, but code is for a single 02) ? Exhaust leak at the manifold ? Hi cat temp due to blockage or failure ?
Should I suspect cat issues as a cause or result (hi temp, blockage) ? they are the original cats and only have 90k miles.
 

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Discussion Starter · #2 ·
P0154 issue was caused by damaged O2 sensor wiring between the sensor and pcm.
 

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So, i know this is kinda old, but...which side was the damaged wiring on? I'm about to try and tackle my P0154 code and suspect a similar problem.

-KP
 
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