Scenario · Warning behaviour
Stop-Start Not Working? It's the Battery.
Stop-start deactivated on the dash? The BMS knows the battery's tired. Mobile AGM replacement and coding across the West Midlands.
Stop-start disabled? Get it working again in one visit.
AGM/EFB stock, BMS coding, no dealer needed.
When stop-start refuses to engage, or the dash shows 'stop-start not available', the battery management system has detected the battery no longer holds enough charge to safely restart the engine after auto-off.
We test capacity on the spot, replace with the correct AGM or EFB, and register the new battery to the BMS so stop-start comes back within minutes of fitting.
Our four-step process
- 1
Fixed quote
By postcode and reg, before we move.
- 2
Load test
So we're not selling you a battery you don't need.
- 3
Correct spec
AGM, EFB or standard flooded, matched to your car, not what's cheapest.
- 4
Coded & clean
BMS registered, terminals greased, old unit recycled.
Key facts, Stop-start not working
- Why it's disabled
- BMS detected battery capacity below threshold
- Test
- Load test and internal resistance measurement
- Fit
- Matched AGM or EFB from van stock
- Coding
- BMS registration via OBD, mandatory on most brands
What we actually see on these jobs
- Stop-start disabling is a helpful warning, not a fault, the BMS is protecting you from a no-start.
- Fitting a standard flooded battery on a stop-start car will fail within months, must be AGM or EFB.
- We register the new battery to the BMS every time; skipping it means the alternator undercharges and it happens again.
Who calls us for this
Drivers of newer petrol and diesel cars, VW, BMW, Ford, Vauxhall, Peugeot, whose dash has been showing stop-start unavailable for a few weeks.
Stop-start not working, specific questions
Q.Is stop-start not working always a battery problem?
Almost always. Occasionally it's a temperature sensor or aux battery, but the vast majority of cases we see are a tired main battery below its rated capacity.
Q.Can I fit a normal battery to save money?
No, stop-start systems need AGM or EFB. A conventional flooded battery will fail in months and the BMS will flag it immediately.
Q.Do you register the battery to the car?
Yes, every time. Without registration the charging system stays calibrated for the old battery and the new one fails early.
General questions
Q.Do you take the old battery away?
Yes, proper lead-acid recycling included with every fit, no extra charge, no landfill.
Q.Do you charge a callout fee just to look?
No blind callout fee. You get a fixed price on the phone based on your postcode and vehicle before we set off, no surprises at the driveway.
Q.Are you insured?
Yes, fully insured with public liability and goods-in-transit on every callout and every battery we fit.
Related guides
In short
Stop-start not working is the car's polite way of asking for a new battery, and we're the polite way of fitting it, coded, on your driveway.
Stranded with a flat battery?
Call now or send a WhatsApp, we'll confirm your quote and dispatch the nearest engineer.