In 2011, Canadian Pacific (CP) Railway decided to replace the visual No.1 Air Brake test with a new Automated Train Brake Effectiveness (ATBE) for condition monitoring of rail cars through both physical inspection and measurements by fixed track-side Wheel Temperature Detectors (WTD). To make the most effective use of technology for operational and maintenance decision-making, the new technology should be shown to be reliable, with outputs that are understandable and interpreted accurately. The present work uses the WTD temperature readings along with records of sensor system failures to develop a method for detecting wheels prone to failure. A set of detector data was checked against neighbouring detectors to improve the classification of a fault with a wheel through multiple measurements and to determine whether there may be a fault with the detector. Studying one train passing consecutive detectors yields useful information about the health of the brakes at each axle of the set of rail cars. Thus, three neighbouring detectors were selected for comparative assessment. Five neighbouring detectors were also selected, but there was no significant databases were employed and the reliability of detectors was modeled. The best fit to the failure distributions was the normal. Mean-time-between failure (MTBF) for all detectors was calculated to be 2.7 years. For an individual detector the MTBF was about three months. But, for winter operations, the MTBF was found to be only 1.8 months. Several recommendations for follow-up analysis work are offered, with suggestions for industrial implementations that should improve overall WTD system reliability.