Intermittent Fault

📖 YOUCANIC Automotive Glossary

An intermittent fault is a malfunction that occurs unpredictably — it may happen once, disappear for days or weeks, then return without any apparent pattern or consistent trigger condition. Unlike soft faults which can be reproduced by recreating specific conditions, intermittent faults seem random. Common causes include loose connector pins that make and break contact with vibration, cracked solder joints inside electronic modules that separate and reconnect with thermal expansion, damaged wire strands that maintain intermittent contact, and corroded connections that conduct variably depending on moisture and temperature. Intermittent faults are the most challenging diagnostic scenario because the problem may not be present during your testing session.

Diagnosing intermittent faults requires a combination of data logging (recording live data over extended driving to capture the moment the fault occurs), DTC history review (looking at freeze frame data for each occurrence to find common conditions), wiggle testing (physically manipulating connectors and wiring while monitoring live data or continuity to provoke the fault), and thorough connector inspection (looking for corroded pins, backed-out terminals, damaged seals, and green oxidation). The YOUCANIC UCAN-II data recording feature captures continuous data that can be reviewed after the fault occurs, revealing the exact parameter changes at the moment of failure.