P1391 code

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Mar 24, 2025 | 02:25 PM

scrapdaddy

Thread Starter

Newbie

Joined: Nov 2021

Posts: 7

Likes: 0

Model: Cherokee (XJ)

P1391 code

Hello everyone, I replaced the rear main seal, rod bearings and a new high volume oil pump on my 2000 Cherokee 4.0L. On the top, I replaced the cylinder head with a new one. I started it, heard a metal clunk sound and rough idle then shut down. It threw the P1391code. I did nothing to either sensor. Question, could I have mis aligned the oil pump shaft thus causing it to throw a CMP P1391 code. Before I drop the pan again, anything else I should look at?

Thank You

Mar 26, 2025 | 07:15 AM

Ricthewrench

Seasoned Member

Joined: Jun 2021

Posts: 457

Likes: 165

From: Ortonville, mi

Year: 97

Model: Cherokee (XJ)

Engine: 4.0

I would totally drop the pan. In case it's a mechanical issue. You may cause more damage if you continue to crank the engine. Turn by hand & feel what's happening would be my first step.

Mar 26, 2025 | 09:14 AM

scrapdaddy

Thread Starter

Newbie

Joined: Nov 2021

Posts: 7

Likes: 0

Model: Cherokee (XJ)

I ordered a Melling reg. oil pump and new camshaft sensor and synchronizer and dropped the pan. Nothing looks out of place and I put number one cylinder on TDC, looks to be in time.