2F43
High2F43 — CAS: Starter Relay Fault
Description
What the Code Means
Code 2F43 points to a faulty starter relay soldered directly onto the CAS module board. The CAS module drives the starter relay directly — there's no separate relay in the starter power circuit.
Over time, after many start cycles, the relay's solder joints on the board crack or the relay contacts themselves wear out. The module can no longer command the starter to engage, and the engine won't crank.
Symptoms
Symptoms
- no starter cranking and no engine start;
- the instrument cluster lights up, but the engine won't crank;
- intermittent starting — the car doesn't fire on every attempt.
Causes and fixes
Diagnosis and Repair
- Confirm code 2F43 with a diagnostic tool (ISTA, INPA).
- Remove the CAS module.
- Replace the starter relay on the module board — this requires soldering. If you're not confident with soldering equipment, send the module to an electronics repair specialist.
- Reinstall the module and check that the engine starts.
Possible secondary damage
Secondary Damage
- long cranking attempts drain the battery;
- if the relay fails completely, the car won't start at all — you'll need a tow;
- in rare cases a stuck relay keeps the starter running continuously, which damages the starter or the flywheel.