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Performing coolant system leak check on Cadillac

April 15, 2025

A small number of 2021 Cadillac XT4 and XT5 vehicles may have a coolant inlet pipe that may present an obstructed threaded hole for the coolant temperature sensor, which could result in the check engine light coming on or a potential coolant leak.

Mike Mavrigian

Related To:

Mitchell 1

If the temp sensor is leaking, replace the thermostat housing inlet pipe using P/N 55507975 and sensor 55488246.

Perform a coolant system leak check. If the cooling system maintains the rated pressure for at least two minutes, then locate the coolant temperature sensor in the engine coolant thermostat housing inlet pipe at the front of the engine.

Pressurize again with the EN-24460-A cooling system pressure tester and observe the sensor to see if it is leaking. If the temp sensor is leaking, replace the thermostat housing inlet pipe using P/N 55507975 and sensor 55488246.

About the Author

Mike Mavrigian | Motor Age Editor

Mike Mavrigian has written thousands of automotive technical magazine articles involving a variety of specialties, from engine building to wheel alignment, and has authored more than a dozen books that crisscross the automotive spectrum. Mike operates Birchwood Automotive, an Ohio shop that builds custom engines and performs vintage vehicle restorations. The shop also features a professional photo studio to document projects and to create images for articles and books.