Transponder Key Programming in Exeter

When the engine turns over but fails to fire, the starter motor and battery are working — the problem lies in the engine management system being told not to run. A failed or unrecognised transponder is one of the first things to investigate, because the immobiliser actively prevents fuel injection until it receives the correct chip signal. The RAC lists immobiliser fault as a leading cause of no-start conditions. We diagnose the exact cause on site with live diagnostic equipment — call with your make and registration and we can advise further before arriving.

The clearest indicator is the immobiliser warning light on your dashboard. If the key light or padlock symbol stays illuminated after inserting the key (rather than switching off within a few seconds), the immobiliser is not recognising the transponder. A fault that appears suddenly on a previously healthy vehicle with no mechanical changes strongly suggests a key or immobiliser issue rather than a fuel or ignition problem. We confirm the exact cause using diagnostic equipment — no guesswork. For deeper ECU or system faults, our immobiliser diagnostics service covers more complex scenarios.

Yes — this is one of the more frustrating aspects of transponder failure. The key may look completely normal, the blade may be undamaged, and the fob buttons may still work for central locking. Yet the chip inside has failed, meaning the engine will not start despite the key appearing fine. Component degradation over time is a genuine cause — chips do not last forever. Water damage that dried out and left no visible trace is another. We test the chip’s radio frequency output directly on site.

Almost certainly yes. Intermittent recognition is a classic early-stage transponder fault. The chip is degrading and producing an inconsistent signal — sometimes strong enough to pass, sometimes not. This almost always gets progressively worse until the key fails completely. Getting it diagnosed and addressed while it is still intermittent is significantly cheaper than waiting for a total failure. See our transponder keys explained guide for more on how the chip signal works.

It depends on the failure mode. If the chip has lost programming (which can happen on some platforms after a battery event), it can sometimes be reprogrammed without replacing the physical chip. If the chip itself has failed physically — cracked, water-damaged or degraded — it needs to be replaced, which means a new key blank with a working transponder. We assess the specific failure before recommending anything. A repair costs less than replacement; we always attempt the lower-cost option first.

Sudden overnight failure without mechanical changes strongly points to an electronic fault — and a transponder or immobiliser issue is high on the list. Other possibilities include a failing battery affecting key recognition on some platforms (particularly VW Group and BMW vehicles), or a software event that has reset key data. We diagnose the root cause on site. Call us with your make, model and the exact symptoms and we will advise before setting off.

Yes — transponder systems have been fitted to most mainstream vehicles since the mid-1990s. Early Ford PATS, early BMW EWS and first-generation VW transponder systems are well within our capability and often faster to work on than modern high-security platforms. Older vehicles are not less important to us — a failed transponder on a 2005 Ford Focus is just as much of a problem as one on a 2023 BMW.

Yes — on certain platforms, a battery that has been completely discharged can cause loss of key programming data. This is particularly seen on some VW Group vehicles and some BMW models. The key itself has not failed — it has simply been dropped from the vehicle’s immobiliser memory. This is usually a straightforward reprogramming job rather than a key replacement. Call us with your registration and we can confirm whether your vehicle is one affected by this.