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Bulletin No.: PIP4158H

Published date: 08/7/2019

Preliminary Information

PIP4158H Low Oil Pump Pressure Due To Sticking Oil Pressure Relief Valve

Models

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Following Aluminum V8 Engine RPOs:

L76, L77, L92, L94, L99, L9H, LC9, LH6, LH8, LH9, LMG, LS2, LS3, LS4, LS7, LS9, LSA, LZ1

Suppersession Statement:

This PI was superseded to change the Condition/Concern. Please discard PIP4158G.

Condition / Concern

Some customers may complain of low oil pressure, no oil pressure, and/or engine noise possible P0521, which may be the result of a sticking oil pump pressure relief valve. In some instances, this may occur intermittently if the valve frees up when the engine cools down.

Recommendations / Instructions

If SI diagnosis isolates low mechanical oil pressure at the oil filter housing and oil pressure sensor, replace the oil pump, flush the oil cooler lines (if equipped).

Clean the inside of the oil pan, change the oil and filter, and re-evaluate the concern.

Notice: If an engine noise is noticed after replacing the oil pump, follow the SI diagnosis and repair the engine as necessary.

Warranty Information

For vehicles repaired under th e Powertrain coverage, use the following labor

operation. Reference the Applicable W arranties section of In vestigate Vehicle History (IVH) for coverage information.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

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