You'll find these codes labelled online as motor relay faults, solenoid faults and pump motor faults. That isn't what Mercedes' own diagnostic list says. Here's the correct meaning of each, straight from the Mercedes SBC fault list.
What each code means
| Code | Mercedes description | In plain English |
|---|---|---|
| C235A | Service threshold reached | A wear limit monitored by the SBC unit has been reached. |
| C235C | Service threshold reached | As above: a different monitored counter, same message. |
| C235E | Service threshold reached | As above. |
| C2359 | Service threshold reached | As above. |
| C2498 | Service threshold reached | As above. C2498 guide. |
| C235D | Check operating time of component A7/3 | Same wording as C249F: the unit's operating-time limit. |
In other words, these are the SBC unit telling you it has reached the end of a monitored service life. They don't point at one specific broken component. That's also why they usually arrive with the grey "Service Brake! Visit Workshop!" message rather than a red warning.
How urgent are they?
They're service warnings, not an emergency in themselves, but they are not optional. The threshold exists because the unit wears: motor brushes, seals and the accumulator. Book the repair rather than living with it for months. If any of these codes appear with pressure codes such as C2131 (pressure reservoir faulty), C25D4 or C26BB (pressure supply), the unit has an active hardware fault and it's more urgent. A red brake warning means don't drive at all.
Can they be reset?
Yes, the counters can be reset with the right software, and a reset makes the warning go away. It also changes nothing inside the unit. We only do a reset (£120, no warranty) after inspection and at the customer's request, because on a worn unit it's a gamble with the brakes.
The fix
| Option | Price | Warranty | Best for |
|---|---|---|---|
| Postal rebuild of your own unit | £430 | 6 months | Grey warning, you or your garage can remove and refit the unit. Keeps your car's coding. |
| Exchange unit | £700 | 12 months | You need the car back fast. Matched to your part number, no core return. |
| Mobile service | from £650 | 12 months | We do the whole job at your address, within ~200 miles of Basingstoke including London. |
| Counter reset only | £120 | None | Only after inspection, on request. It clears the warning but repairs nothing. |
Send us the full list of codes and the part number on your unit's label (WhatsApp 07404 487674) and we'll tell you straight which route fits. Full table: Mercedes SBC fault codes.