Skoda Fabia: Stop-start system failing — battery sensor and crankshaft sensor

The stop-start system on the 1.0 TSI Fabia fails often and unusually early, with reports from as little as 15,000 km. The two usual causes are the battery monitoring sensor and the crankshaft sensor, neither of which is expensive on its own. What makes this worth understanding rather than dismissing is what else those parts do. The battery sensor tells the car how healthy the battery is, and when it is wrong the car can mismanage charging, which shortens the battery's life and produces electrical oddities that look unrelated. The crankshaft sensor is a running-critical part — the same sensor the engine needs to fire at all — so a car that has stopped doing stop-start is sometimes giving you early warning of a sensor on its way out.

• Stop-start no longer switching the engine off at a standstill
• Stop-start message on the dash saying the function is unavailable
• Battery warning light, or the battery going flat unexpectedly
• Engine cutting out or stumbling while driving
• Hard starting, or the engine refusing to fire

Test the stop-start deliberately rather than waiting to notice it. Get the engine fully warm, then come to a complete stop with your foot on the brake at a set of lights or in a quiet street, and confirm the engine actually switches itself off — then that it restarts cleanly and instantly when you release the brake. Do this several times during the drive. If it never switches off, look at the dash for a message explaining why, since the car usually tells you. Note that a genuinely cold engine or a very hot day will suppress it legitimately, so judge it warm and in ordinary conditions. Watch for a battery warning light at any point, and note any stumble or momentary cut while driving. Ask the seller how old the battery is and whether it has been replaced — a battery fitted without the car being told about it is a common cause of exactly this. Ask whether the battery has ever gone flat. If a workshop inspection is possible: ask for the stored faults to be read, which names the sensor directly.

$250 to $1,200 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Does the stop-start still work, and when did it stop if not?”
• “How old is the battery, and was it replaced at a dealer?”
• “Has the engine ever cut out or been hard to start?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.