What this checklist covers
The EV Diagnostic Process Checklist is a 15-point scorecard for diagnostic equipment, fault code reading, battery health checks, software version, charging system testing, and repair approval. Each criterion is scored from 1 to 5 on what the auditor sees on the day, and every gap goes into an action plan with an owner and a close date.
AutoSmart tip: EV diagnostic accuracy is directly dependent on software version — a vehicle running an outdated BMS firmware may present fault codes that have been updated or reclassified in a newer version, leading to unnecessary component replacement or misdiagnosis. Always check and update vehicle software before concluding an EV diagnostic session, and always verify the diagnostic tool software version matches the OEM’s current requirement.
The checks
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Diagnostic equipment and software version
- Is the OEM-specified diagnostic tool available at the dealership and capable of communicating with all EV models currently in the service portfolio?
- Is the diagnostic tool updated to the current software version, with version history confirming updates were applied within the OEM-specified timeframe after each release?
- Is the vehicle's software version checked at the start of every EV diagnostic session, with an OTA update applied (or flagged) if the vehicle is running an outdated version that may affect diagnosis accuracy?
- Is the diagnostic tool calibrated or self-tested as required, with calibration records available and no out-of-date calibration status in active diagnostic use?
Fault code reading and battery health check
- Is a full vehicle scan (all control modules, not only the primary fault system) performed for every EV diagnostic session, capturing all stored and pending fault codes?
- Are fault codes interpreted using the OEM diagnostic database rather than generic code readers, ensuring EV-specific codes are correctly identified and not misattributed to generic system faults?
- Is a battery state-of-health (SoH) check performed for all EV diagnostic sessions where a battery-related customer complaint or range concern is reported?
- Are battery cell balance, temperature history, and BMS fault flags reviewed as part of the battery diagnostic, not only the headline SoH percentage?
Charging system test
- Is the vehicle's onboard charger and charging control system tested as part of any diagnostic session involving a charging complaint, using the OEM diagnostic routine for charging system verification?
- Is the charging port and cable connection inspected physically for damage, contamination, or corrosion as part of every charging-related diagnostic session?
- Is the vehicle tested on an actual charger (AC and DC where relevant) during the diagnostic session, rather than relying only on static diagnostic data when a real-world charging fault is reported?
Root cause analysis and repair approval
- Is a root cause identified for every EV fault — distinguishing between software fault, hardware failure, high-voltage system issue, and charging infrastructure problem — before a repair recommendation is made?
- Is the repair recommendation reviewed by a senior technician or team leader for all EV faults involving the high-voltage system, battery, or powertrain before the customer is committed?
- Is customer approval obtained for the specific repair recommended — with the diagnosis, proposed fix, and cost clearly explained — before any HV system component is disturbed?
- Is EV diagnostic accuracy tracked through a comeback metric specifically for EV faults, allowing identification of recurring misdiagnosis patterns by model or fault type?
How to run it
How the scoring works
Before the visit, fill in the dealer or centre, the auditor, the date and the audit cycle. Then score each of the 15 checks from 1 to 5 on what you see on the day, not on what the site aims for, and add them up out of 75.
- 1Not in place
- 2Attempted
- 3Defined
- 4Managed
- 5Fully sustained
- Green60–75 · 80–100%Compliant. Keep the standard.
- Amber38–59 · 50–79%Improvement needed: a structured action plan within 30 days.
- Red0–37 · Below 50%Priority intervention, escalated to regional management.
Then close every gap
Each gap goes into the action plan tracker and moves through four stages until the auditor closes it.
- 1PendingOwner and close date set
- 2In progressWork under way, evidence gathered
- 3CompletedEvidence submitted for review
- 4ApprovedVerified and closed by the auditor
