Cadillac Repair Questions? Ask a Mechanic for Answers ASAP
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Some customers may complain of a low oil pressure message/light on the dash and a technician may find a P0521 DTC in the ECM.
If this concern is encountered, follow SI diagnosis. If it indicates that the Tech 2 oil pressure parameter is low but proper oil pressure is present at the oil filter housing, inspect the Valve Lifter Oil Filter for debris/sludge that could be restricting oil flow to the oil pressure sensor before replacing any parts.
Follow the Valve Lifter Oil Filter Removal and Installation Procedure to remove the filter for inspection. If the filter is plugged, it can normally be cleaned with brake/contact cleaner and light shop air. If it cannot be cleaned for some reason, replace it using the part number listed in the parts catalog. Do not replace the complete Valve Lifter Oil Manifold just because the filter is plugged.
This PI was superseded to update model years. Please discard PIP4158B.
Some customers may complain of low oil pressure, no oil pressure, and/or engine noise, 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.
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.
These are problems that your GM dealer is familiar with, if the truck is still under powertrain warranty, definitely refer it to your local dealer and see if they'll address it at no charge.
Important: Do not allow dirt or debris to enter the oil passages of the manifold. Plug, as required.