Testing depends on the component.
Some parts can be assessed thoroughly on a bench. Others can only be judged properly once they are on a vehicle. Rather than claim everything is “fully tested”, we set out what we actually do for each type of component — and where the limits are.
No supplier can guarantee the remaining service life of a used component. What testing does is catch the units that are already faulty, already damaged, or already outside acceptable condition — so those never reach you. That is what our checks are for, and it is why eligible parts also carry a replacement warranty.
Alternators
One of the components that bench-tests best, because the unit can be driven and its output measured directly.
- Visual inspection of housing, mounting ears, connector and rear cover
- Pulley and bearing assessment for roughness, play or noise
- Free-wheel (overrunning) pulley function where fitted
- Electrical output testing and regulator behaviour across the operating range
Limit: a bench test confirms the unit charges correctly today. It cannot predict how long it will keep doing so.
Starter motors
Bench testable for engagement and current draw, which catches most of the common failure modes.
- Visual inspection of housing, nose cone, mounting flange and terminals
- Pinion and drive gear condition, including tooth wear and free rotation
- Solenoid operation and pinion throw
- Bench test for motor operation and current draw under no load
Limit: a no-load bench test does not reproduce the load of cranking a cold engine. Brush wear in particular can show up later.
AC compressors
Assessable mechanically, but not fully testable for cooling performance outside a charged system.
- Visual and mechanical inspection of body, ports, mountings and shaft seal area
- Pulley and clutch assessment for bearing noise, play and clutch face condition
- Shaft rotation check for seizure, roughness or excessive drag
- Clutch coil continuity and engagement check
Limit: full performance testing requires the compressor installed in a charged, leak-free system. Correct installation — flushing, replacing the drier, correct oil charge, proper evacuation — matters more here than on almost any other part.
Brake calipers
Safety-critical, so we are conservative. Anything we are not confident about is not offered.
- Physical inspection of body, bleed nipple, mounting points and slide pins
- Piston movement and retraction
- Seal, dust boot and bore condition; corrosion and leakage checks
- Electric parking brake actuator function where fitted
Limit: brake components must be fitted by a competent workshop, bled correctly and road-tested. We will decline a sale rather than supply a caliper we are unsure of.
Sensors
Testable to varying degrees depending on the sensor type and what it measures.
- Visual inspection of body, connector pins and sealing
- Electrical continuity and resistance checks where the sensor type allows
- Signal or output testing where equipment and reference values are available
- Part number verification against the application
Limit: many sensors only behave meaningfully under real operating conditions — temperature, pressure, engine speed. A bench check confirms the sensor is electrically sound, not that it reads accurately in service.
ECUs and control modules
The hardest category to validate, and the one where we are most explicit about the limits.
- Visual inspection of housing, connectors, pins and any sign of water ingress or previous repair
- Hardware and software number verification against your application
- Donor vehicle history where it is available
- Vehicle-level testing where that is practical for the specific unit
Limit: a control unit generally cannot be fully validated off the vehicle, and many require coding, programming or immobiliser matching by a workshop with the right equipment before they will function. Because of this, certain electronic parts carry stricter purchase and warranty conditions, which we state in writing before you buy.
What you get with every part
- Photographs of the actual unit, including labels and part numbers where they are legible
- A written note of the checks carried out on that specific component
- Condition notes covering anything visible that you should know about
- Confirmation of whether the part is warranty-eligible, before you commit
Tell us what you need. We’ll find it for you.
Send your vehicle details and a photograph of the part. No OEM part number required — we work it out from what you give us.