These instructions apply to the Ford Focus Mk IV (DEH) 2019-Present.
For other models, please choose your vehicle here.
The Ford Focus (Mk4, 2019–present) carries the same owner-accessible cluster Self-Diagnostic Mode as earlier Focuses, adapted to this generation’s digital and part-digital displays. Ford sometimes calls it engineering test mode. You open it with the steering-wheel OK button and the ignition — no scan tool — for a gauge sweep, display and bulb check, live engine data and stored cluster fault codes.
What the self-test is and what it shows
This hidden routine runs the Mk4 cluster through a full set of self-checks: a gauge sweep, an LCD test that lights every display element, and a bulb/LED test for the warning lamps. It then steps through diagnostic and live-data screens, which on the Mk4 include:
- ROM level and NVM (EEPROM) level — cluster software/data references
- DTCs — stored cluster Diagnostic Trouble Codes
- Road speed (MPH/km/h), RPM, fuel volume and fuel flow
- Engine coolant temperature and battery voltage
- ABS / electronic brake distribution status flags, illumination settings and crank sense
It is the cluster checking itself and the data feeding it, a fast and free first look before a workshop visit.
How to enter the hidden diagnostic menu
- Sit in the driver’s seat with the ignition fully OFF.
- Press and hold the OK button on the steering wheel.
- While holding OK, turn the ignition switch from position 0 to position II (ON). On keyless cars, press START once with your foot off the brake so only accessories power up — do not start the engine.
- Keep OK held until TEST appears in the cluster.
- Release OK within about three seconds of TEST showing, or the cluster exits the mode immediately.
Reading the gauges, voltage and codes
Press the OK button (or use the arrow button) to move through and skip tests. Begin with the gauge sweep, LCD test and bulb test — a dead element or unlit lamp confirms a cluster hardware fault rather than a sensor issue. Continue to the live-data screens for road speed, RPM, fuel volume/flow, coolant temperature and battery voltage. A healthy battery at rest reads about 12.4–12.7 V. The DTC screen lists any stored cluster codes; note them down before exiting.
How to exit
Turn the ignition to OFF to leave Self-Diagnostic Mode. The cluster returns to normal operation at the next start and nothing you viewed has been altered.
Frequently Asked Questions
Does the Mk4’s full digital display change the procedure? No. Whether your Focus has the analogue-plus-LCD cluster or the larger digital one, the OK-button entry sequence is the same; only how the screens are drawn differs.
TEST appears then disappears at once — why? You held OK too long. Release it within roughly three seconds of TEST showing, or the cluster drops out of the mode.
What is the ROM/NVM level for? Those screens show the cluster’s software and data reference levels. They are useful to a technician confirming a cluster’s configuration; most owners can simply skip past them.
Will this reset the service or oil-life reminder? No. The self-test only reads and displays; service intervals and trip data are untouched.
Are the DTCs here the full engine codes? No — they are cluster-level codes. If a powertrain warning is lit, run a full OBD-II scan of the engine ECU as well.
To decode any cluster trouble codes you find and judge how urgent they are, see autodtcs.com.
Independent guide — not affiliated with Ford. Always follow your official service manual and safety precautions. Read our full disclaimer.