Jeep Wagoneer's MPG Drop Linked to Engine Warning Light

Had similar symptoms on a Jeep Grand Cherokee 2018 with the 3.6L engine. The variable timing system was not functioning correctly, creating poor fuel economy and triggering the check engine light. After proper diagnosis, it turned out to be a VANOS failure caused by a defective camshaft solenoid valve. The symptoms included low power during acceleration and engine misfire at idle. The timing chain was inspected and found to be in good condition, but the solenoid was not receiving proper power supply. The repair required replacing the solenoid valve and cleaning the oil passages to ensure proper oil flow to the VANOS system. This was a serious issue that needed immediate attention to prevent potential engine damage. The symptoms match what you are describing, and postponing the repair could lead to more extensive engine problems. Would recommend getting a diagnostic scan to confirm the specific fault codes before proceeding with any repairs. A failed VANOS solenoid can be confirmed through proper testing of the electrical signals and oil pressure readings.

Thanks for sharing your experience with the VANOS system. The symptoms you described match exactly what I dealt with. My case ended up requiring a complete solenoid replacement as well, along with a thorough cleaning of the oil passages to prevent future oil sludge buildup. Do you remember what the total repair cost was for your fix? Also curious if youve had any recurring check engine light issues since the repair was completed?

The complete repair with the Inlet VANOS mechanics ended up being 250 Euro for parts and labor. My situation involved replacing one faulty camshaft solenoid valve that was not getting proper power supply. The good news is that since having the repair done, the check engine light has stayed off completely. The variable timing system is now working as intended, and both fuel economy and engine performance have returned to normal. No more low power issues during acceleration or rough idle problems. Regular oil changes with the recommended grade have helped prevent any oil sludge buildup in the VANOS system. No recurring issues in the 8 months since the fix was completed. The repair shop did a thorough job cleaning all the oil passages while they had everything apart, which probably helped ensure everything keeps running smoothly.

After getting several opinions, I finally took my Jeep to a different shop. The mechanic confirmed it was indeed a VANOS solenoid issue through proper diagnostic testing. The repair cost came to 475 Euro total, which included replacing the faulty solenoid and a complete cleaning of the oil passages. The check engine light disappeared right after the fix, and my fuel economy is back to normal. The engine now runs smoothly without any power loss or rough idling. It has been about 6 weeks since the repair, and everything is working perfectly. Looking back, I am glad I trusted my gut and got that second opinion. The original shop wanted to replace additional parts that werent actually necessary. The new mechanic was thorough and honest about what really needed fixing.