Before You Clear Codes: A Pre- and Post-Repair Scan Report Checklist

Before clearing codes, save the original scan report, each code's status, available freeze-frame data, and emissions readiness results. After repair, repeat the relevant scans and tests, then save a separate report that explains what changed and what still needs attention.

A useful pre- and post-repair scan report connects the customer's complaint to the diagnostic evidence, repair, and verification. A blank code list immediately after erasing memory leaves that story unfinished. This checklist helps DIY owners and repair shops build a record they can actually use.

What a Pre-Scan and Post-Scan Should Tell You

A pre-scan records the vehicle's condition before repair or diagnostic changes. A post-scan records findings after the work and any required verification. Keep both under the same vehicle and repair order, with separate timestamps.

Start by identifying the scan's scope. Generic OBD-II diagnostics cover emissions-related information; enhanced diagnostics can access additional modules when the tool supports the vehicle. An engine-code reader's result cannot stand in for an ABS, airbag, body, and network scan. When comparing professional scan tools, check the specific modules you need to access and whether their results can be saved.

Report item	Before repair	After repair
Vehicle and job	Confirm VIN, mileage, complaint, and repair order	Match the vehicle and job; record new mileage and time
Scan coverage	List scanned modules and access gaps	Compare the same scope and explain differences
Trouble codes	Save exact codes, modules, descriptions, and status	Identify returning, remaining, and newly recorded codes
Supporting evidence	Save available snapshots and relevant data	Attach comparable test results
Emissions information	Record MIL command and readiness	Recheck readiness and permanent codes where supported
Repair record	Describe the concern and diagnostic plan	State work completed, verification, and open items

Treat this as an editorial recordkeeping checklist. Vehicle manufacturer procedures determine which diagnostic tests, resets, calibrations, or other checks the repair requires.

Before You Clear Codes Save These Seven Things

1 Confirm the Vehicle and the Complaint

Record the VIN, model year, make, model, engine or powertrain, mileage, and repair order. Verify automatic vehicle identification against the actual vehicle. Add the scanner model and relevant software version so another person can understand the testing setup.

Describe when the symptom happens: cold start, warm idle, acceleration, braking, or intermittent operation. Include recent battery work, a jump-start, prior repairs, and known warning lights. These notes help make later comparisons meaningful.

2 Save the Complete Initial Scan

Scan the systems relevant to the complaint and repair using supported coverage. Record which modules responded, which could not communicate, and which were inaccessible or unsupported. For work spanning several systems, compare Autel advanced diagnostic tools by their supported modules and reporting functions; confirm these for the exact vehicle.

Label a limited engine scan accurately. If a module fails to communicate, record the gap and investigate the connection, vehicle identification, power supply, access requirements, or module/network condition as appropriate. Do not mark that module fault-free.

3 Preserve Exact Codes and Status Labels

For each finding, save the code, reporting module, scanner description, and displayed status. Retain labels such as current, stored, pending, or history exactly as shown; their meaning can vary across manufacturers and systems.

Do not replace the original evidence with a handwritten list of code numbers. A code identifies a detected condition and the system reporting it. The diagnostic procedure establishes the cause, which may involve wiring, power supply, operating conditions, or a component.

4 Export Freeze Frame and Relevant Live Data

Save available freeze-frame records before erasing anything. These snapshots may help establish the conditions under which a fault was recorded. Check whether exporting the main report actually includes them; save separate files or screenshots when needed. The freeze-frame guide explains how these snapshots help interpret the conditions behind a fault.

Choose live-data recordings that answer the diagnostic question, with units and operating conditions attached. A warm-idle recording and a cold-start recording are different comparisons. Mark unavailable data as unavailable rather than inventing a value or assuming it is normal.

5 Record MIL and Readiness Information

Save the commanded malfunction indicator lamp, or MIL, status and note the observed check-engine light. Record supported emissions monitors and their completion status. If the scanner offers separate readiness views, label which view you saved.

Autel's MK900-BT manual explains that emissions code clearing removes diagnostic information, including freeze frame, and resets readiness. It also distinguishes readiness since codes were cleared from readiness during the current driving cycle. Capture this information before using Erase Codes.

6 Separate Permanent Codes From Other Findings

Where supported, save permanent emissions DTCs separately. They can remain after an ordinary clear command and after a successful repair while the vehicle completes its verification.

California BAR explains that permanent DTCs cannot be erased with a scan tool or battery disconnection. The underlying fault must be corrected and the vehicle must rerun the relevant monitor successfully. Keep this distinction visible in the report.

7 Open the Saved Files Before Proceeding

Export the pre-scan and open it to confirm that it contains the correct vehicle, date, module results, and attachments. Use a filename such as RO1042_PRE_2026-10-28_0915.pdf; keep customer details within the shop's normal recordkeeping system.

A report that remains only in an unsaved session can be difficult to recover. Preserve a separate original before clearing, disconnecting components, or making changes that could alter the evidence. See Autel pre-scan and post-scan reports for an example of a paired reporting workflow.

Check the saved report and its attachments before erasing diagnostic information.

When Should You Clear the Codes

Clear codes when the diagnostic or repair procedure calls for it, after preserving the original evidence. Record the reason, time, and affected systems. Some diagnostic tests require a deliberate clear before checking recurrence; identify that step as part of testing.

Follow the vehicle and scanner instructions for ignition state and operating conditions. Read the confirmation message carefully, especially when a command affects multiple modules. Code erasure, service reminders, adaptations, coding, and programming are distinct operations; select the function the procedure requires.

If you already cleared the codes, record that fact. Save the current scan, describe any symptoms that remain, and continue with the appropriate diagnosis. Evidence saved earlier may still help, but a newly generated report cannot recreate an unsaved original freeze frame.

After Repair Verify These Six Items

1 Document the Work and Required Procedures

State what was diagnosed, what was repaired, and which checks supported that decision. Attach required setup, relearn, or calibration records when applicable. A scan report alone cannot establish that those procedures were completed.

For brake, airbag, ADAS, or high-voltage repairs, use the applicable manufacturer procedure and qualified personnel. The post-scan forms one part of the repair record alongside the required physical and functional checks.

2 Repeat a Comparable Scan

Use the same vehicle identification and scan scope where practical. Explain any changed tool, software, module availability, or access limitation. Compare module-level findings rather than only the total number of codes. On a reporting-capable tablet such as the Autel MaxiCOM MK900-BT, link the before-and-after records to the same repair order and retain separate exports for comparison.

If a module responded before repair and now does not, investigate that change. A smaller fault count alongside reduced coverage needs explanation.

3 Save Returning and New Codes Before Clearing Again

Read codes after the repair and any procedure-directed clearing. Save recurrence and new findings with their status and conditions. Repeatedly erasing them can obscure a useful pattern.

An immediate return calls for further diagnosis under the relevant procedure. If a fault occurs only under particular conditions, document whether those conditions were reproduced during verification.

4 Check the Original Symptom and Relevant Data

Verify the customer's concern and repeat the measurements or functional tests that matter to the repair. Compare data under similar conditions and use manufacturer specifications for evaluation.

A road test may be appropriate when the vehicle is safe to drive and the procedure requires it. Record the conditions and outcome. Avoid a generic mileage target: different faults and monitors need different enabling conditions.

5 Recheck Readiness and Permanent Codes

Readiness indicates whether emissions self-tests have completed. Record any incomplete monitors and whether additional verification remains. BAR's OBD test reference explains that monitor completion depends on operating conditions and functioning components.

Check the rules for the vehicle's inspection jurisdiction before an emissions appointment. A check-engine light that stays off immediately after clearing does not establish inspection readiness, and no universal drive distance guarantees that all monitors will complete.

6 Save the Final Report and Open Items

Export the post-scan separately and retain the pre-scan. Include the symptom check, remaining codes, access gaps, incomplete tests, and agreed next action. For customer handoff, explain whether repair verification is complete or further testing is needed.

 

The verification record should connect the repair to the tests actually performed.

How to Read a Report That Looks Clean

Use precise wording when describing results:

Displayed result	Practical interpretation	Follow-up
No DTCs found	No codes retrieved within the scanned scope at that time	Confirm coverage and relevant verification
No communication	The tool did not establish communication	Investigate and document the access gap
Not supported	That function or system was unavailable in this session	Confirm vehicle equipment and tool coverage
Monitor not ready	The emissions self-test has not completed	Follow applicable verification guidance
Permanent DTC remains	An emissions fault record remains pending vehicle verification	Review repair evidence and relevant monitor results

For example, a report might say: “No DTCs retrieved from responding modules. The original symptom was not reproduced during the documented test. One emissions monitor remains incomplete.” This is illustrative wording, not a vehicle test result. It tells the next reader what was checked and what remains open.

 

Scan coverage and test completion determine how much a result can tell you.

Which Autel Scanners Support Pre and Post Scan Reports

The comparison matrix marks the following Autel models for Pre & Post Scan. Use this list to shortlist a scanner, then confirm reporting availability for the exact unit, software, and sales region. Vehicle and module coverage still need a separate check.

Model group	Models marked for Pre & Post Scan
MaxiCheck 900	MX900, MX900-TS
MaxiCOM 900	MK900, MK900-BT, MK900-TS
MaxiDAS 900	DS900, DS900-BT, DS900-TS
MaxiPRO 900	MP900, MP900E, MP900E kit, MP900-TS, MP900-BT, MP900Z-BT, MP900-BT kit
906 Pro models	MS906 Pro, MS906 Pro-TS, MK906 Pro, MK906S Pro, MK906 Pro-TS, MK906S Pro-TS
Later 908 models	MS908S II, MS908S Pro II, MK908 Pro II
Later Elite models	MaxiSys Elite II, MaxiSys Elite II Pro
MS909 and above in the matrix	MS909, MS919, Ultra, Ultra Lite, Ultra Lite S

Model reference: diagnostic-tablet comparison matrix, Pre&Post Scan row; reviewed October 28, 2026. Models absent from this list have not automatically been classified as unsupported.

Check Older Models by Device Version

The matrix also marks MS906, MS906S, MS906TS, MS906BT, MK906BT, MS908, MS908 Pro, MS908S, MS908S Pro, MK908, MK908P, and the original MaxiSys Elite. However, its note excludes Android 4 devices, while Autel's legacy comparison lists reporting for some older models, with regional restrictions. These sources do not establish one rule for every older unit. Confirm the device's operating system, regional software, and actual Pre/Post reporting menu with Autel before relying on it.

Choosing a Tablet for Your Reporting Needs

For an independent shop comparing another reporting-capable tablet, consider the Autel MaxiSys MS906 Pro. The matrix marks it for this function, and its product listing describes customizable Pre/Post scans. Compare the additional diagnostic functions you actually need; reporting alone does not justify a higher-specification tool.

Before choosing a model, confirm the vehicle's VIN, model year, region, powertrain, required modules, and software version before purchase. Neither a support tick nor a report export guarantees complete vehicle coverage.

FAQ

Does a post-scan replace a road test

No. The required verification depends on the complaint and repair. Save the scan alongside any relevant functional checks, road test, or calibration results.

Can a basic OBD2 reader produce a useful record

Yes, within its supported scope. Save available emissions codes and data, and label the record clearly. Additional module coverage requires a compatible tool.

Should every remaining code be cleared before handoff

Document and assess remaining findings first. Explain unresolved concerns, permanent emissions codes, and any further work. Follow the applicable repair procedure.

What if my scanner has no PDF export

Preserve screenshots or a structured written record with vehicle identification, timestamps, modules, codes, status, and supporting data. Confirm that each saved file is readable.