Buying a Used E46, E39 or X5? A 15-Minute Pre-Purchase Scan With PASOFT

A seller can clear the check engine light before you arrive, but they can't easily hide everything. A full scan of every module takes about 15 minutes with PASOFT and a laptop, and it can save you from an expensive surprise. Ask the seller first, then use this checklist.

1. Identify the car

With the car off, connect the cable to the car and your laptop and open PASOFT. Switch the ignition ON and click Continue. PASOFT runs Car ident and reads the VIN, model, engine, gearbox and factory equipment. Check that they match the ad and the paperwork. A different engine or gearbox than advertised is worth asking about.

2. Scan every module

Click Close to reach the main screen, then click Scan! to check all modules. To look closer at one module, double-click it in the list (or pick it from the Units menu) and open Errors..., which shows present and past faults. Pay attention to:

• DME (engine): misfires, lean codes, oxygen sensor faults
• EGS (automatic gearbox): any transmission faults
• ABS / DSC: wheel-speed sensor and pump faults
• SRS (airbags): any airbag fault
• IKE, LCM, ZKE: cluster, lighting and body electronics faults

A car with almost no stored faults in any module may have been cleared recently. That's not proof of a problem, but it's worth asking why.

3. Check the keys

Open the EWS module and click Keys. On EWS3 cars this shows the status of every key slot, so you can see how many keys have been used. Compare that with the number of keys the seller is handing over. Missing keys are a security risk and expensive to replace.

4. Watch live data on a test drive

Have a passenger open the DME, click Live data and watch the values, especially coolant temperature. Click + data group for the second screen. On many BMWs of this era the dash gauge is buffered and can hide overheating (see our coolant temperature guide).

5. Save the log

PASOFT keeps a log of the session (see View log). Save it before you leave. If you buy the car, it's your baseline. If you don't, it's a record of why.

Ask first: always get the seller's permission before connecting anything to their car, and don't clear any codes or change any settings on a car you don't own.

Get set up

The PASOFT Scanner Kit includes the USB interface, cable and PASOFT software, with free remote setup support. If your car has the round 20-pin port under the hood, get the Kit + 20-Pin Adapter Bundle instead. Questions about your car? Email info@bmwpasoft.com with your model and year.