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Repair-order writing guide

Automotive Three C's: Complaint, Cause, and Correction.

The Three C's turn a repair into a record someone else can understand. Here is how to document what the customer reported, what testing proved, and what work resolved it.

What do the Three C's mean?

Complaint records the symptom or request. Cause records the verified reason for that condition. Correction records the repair performed and the verification completed afterward.

01

Complaint

What is happening, when it happens, and any conditions that make it repeatable.

02

Cause

The result of diagnosis—not a guess or a rewritten version of the complaint.

03

Correction

The work performed, important measurements or parts, and final verification.

Five complete Three C's examples

1. Brake vibration

ComplaintCustomer states steering wheel shakes while braking from highway speeds.

CauseRoad tested vehicle and duplicated vibration during moderate braking. Measured front rotor lateral runout; left front rotor measured outside specification. Pads have uneven contact pattern.

CorrectionReplaced front brake pads and rotors, cleaned hub mounting surfaces, torqued wheels to specification, burnished pads, and road tested. Brake operation is normal and vibration is no longer present.

2. Check-engine light and misfire

ComplaintCustomer states check-engine light is on and engine runs rough at idle.

CauseScanned vehicle and found cylinder 2 misfire code. Monitored misfire counters and confirmed cylinder 2 misfire at idle. Swapped ignition coil with cylinder 3; misfire followed coil.

CorrectionReplaced failed ignition coil on cylinder 2, cleared diagnostic codes, and performed road test. No misfires returned and engine now idles normally.

3. Battery goes dead overnight

ComplaintCustomer states battery is dead after vehicle sits overnight.

CauseBattery tested serviceable after charging. Parasitic-draw test measured 410 mA after modules entered sleep mode. Isolated draw to glove-box lamp circuit; switch was not opening with door closed.

CorrectionReplaced glove-box lamp switch and repeated sleep-current test. Draw stabilized at 24 mA. Verified vehicle starts normally after extended key-off period.

4. Air conditioning not cold

ComplaintCustomer states air from vents is warm with A/C selected.

CauseVerified compressor operation and low refrigerant pressures. Leak inspection found refrigerant dye at condenser seam. No other leaks observed.

CorrectionReplaced condenser and required seals, evacuated system, confirmed vacuum held, and recharged to specified capacity. Center-vent temperature now reaches 43°F at recorded shop conditions.

5. Scheduled maintenance

ComplaintCustomer requests engine-oil and filter service and tire rotation.

CauseVehicle mileage and maintenance reminder indicate scheduled service is due.

CorrectionChanged engine oil and filter, set oil level, rotated tires, adjusted tire pressures, inspected for leaks, and reset maintenance reminder.

How to make the notes stronger

  • Record how the symptom was duplicated instead of writing only “verified concern.”
  • Include relevant codes, measurements, test results, or inspection findings.
  • Separate what was observed from what was concluded.
  • Name the repaired component and the verification performed after the repair.
  • Avoid claiming the vehicle is completely fixed when the requested diagnosis or repair was declined.
Important: Keep every note truthful to the work actually performed. Specifications, procedures, and warranty documentation requirements vary by manufacturer and shop.

Copyable Three C's template

ComplaintCustomer states [symptom] occurs when [operating condition].

CauseVerified [symptom]. Tested [system/component] and found [specific result, measurement, or fault].

CorrectionPerformed [repair]. Verified by [post-repair test]; [final result].

Keep the finished note attached to the RO

A good note is more valuable when it stays connected to the repair order, date, hours, and customer history. RoTracker lets technicians keep that record together, and Tech Pro can help turn rough notes into a structured Three C's draft for review.

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