The P0615 code in your 2022 Mazda CX-5 indicates that the ECM has detected a malfunction in the starter motor relay control circuit. This circuit is responsible for engaging the starter when you press the start button. While your CX-5 may still start, the ECM has identified an issue with how the starter relay circuit is performing.
Starter Relay Circuit Overview
When you press the start button in your CX-5, the ECM verifies conditions are safe for starting (brake pedal pressed, key fob present, transmission in Park) and then activates the starter relay. This relay carries the high current needed to engage the starter motor. P0615 indicates a problem in this control pathway.
Common Causes
A worn or stuck starter relay is the most frequent cause. Corrosion or damage in the wiring between the ECM and starter relay affects circuit operation. The starter motor itself, if drawing excessive current, can cause relay circuit issues. In some cases, the ECM's starter relay driver circuit has failed.
Symptoms You Might Experience
Starting may become inconsistent—sometimes the engine starts immediately, other times it requires multiple attempts. You might hear clicking but no engine cranking. The check engine light illuminates. In some cases, the vehicle starts normally but the code appears due to circuit monitoring detecting marginal values.
Diagnostic Procedure
Test the starter relay by swapping it with an identical relay if accessible. Check wiring for the starter relay control circuit for shorts, opens, or high resistance. Measure starter current draw to identify if the motor itself is causing problems. Using Mazda IDS-II, monitor the starter circuit operation and verify relay command status matches actual operation.