Immobiliser Diagnostics and Repair in Leicester
Inta-Lock diagnoses and repairs factory immobiliser faults at your vehicle in Leicester, finding which part of the system stops the engine from starting.
Get a price for your car
Send the details and Matt comes back with a price.
An immobiliser is the factory security system that lets the engine run only after it recognises the coded key. When that recognition fails, the car does not start, even with the correct key in your hand.
Matt is with you within the hour in Leicester, and the same day across Leicestershire. The phone is answered 24 hours a day on 0116 442 2084, and a quote is agreed before work begins.
Signs That Point to an Immobiliser Fault
Four signs point to the immobiliser and away from the starter motor, the fuel system or the vehicle battery.
Three Safe Checks Before the Call
Three checks take a few moments at the car and tell Matt where the immobiliser fault is likely to sit before he sets off.
- Try the spare key. A spare key that starts the engine places the fault in the first key. A spare that fails the same way points to the vehicle.
- Watch the security light. Switch the ignition on and note whether the key or padlock symbol goes out, stays lit or flashes.
- Look at the vehicle battery. A dim dashboard or a slow, laboured crank points to low battery voltage, which produces immobiliser warnings of its own.
Repeated cranking drains the battery and adds a second fault to the first, so two or three attempts are enough. Tell Matt what each check showed when you call.
Immobiliser Fault Diagnostic Matrix by Symptom
Seven symptoms cover the immobiliser faults a driver sees, and each one leads to a different test, a different meaning and a different next action.
| What the car does | What is tested | What the result means | Next action |
|---|---|---|---|
| The security light flashes, the engine cranks and does not fire | The transponder chip in the key is read at the reader coil, and the spare key is tried where one exists | A spare that starts the engine places the fault in the first key, not in the vehicle | The first key is tested further, then reprogrammed or replaced |
| Two keys are rejected in the same way | The reader coil signal, its connector and the stored immobiliser fault codes | Two keys failing together point to the vehicle side of the system | The reader coil, the wiring or the immobiliser module is traced before any key work is quoted |
| The engine starts and stops after a second or two | The key authorisation status in live data while the engine is started | On many cars the engine control unit cuts the engine when no release arrives from the immobiliser | The communication between the immobiliser module and the engine control unit is checked |
| The fault follows a flat or changed vehicle battery | Battery voltage at rest and while cranking, then the stored fault codes | Low voltage raises immobiliser warnings with no failed part, and on some vehicles the key loses synchronisation after a power loss | The battery is put right first, and key synchronisation is restored where the vehicle supports it |
| The car starts on some days and not on others | The fault code history, and the reader coil connector and wiring while the signal is watched | An intermittent fault points to a connection, a coil or a key chip that fails part of the time | The weak part is identified, or the findings are reported where the fault does not show during the visit |
| A push button start car reports no key detected | The fob battery, the fob signal and a start with the key held at the backup reader position the manufacturer marks | A start from the backup position shows the chip is sound, so the fob power or the proximity antenna circuit is at fault | The fob battery is renewed or the fob repaired, or the antenna circuit of the vehicle is traced |
| Nothing happens, no crank and no security light | Battery voltage and the starter circuit, ahead of any immobiliser test | The fault lies outside the immobiliser | The finding is reported before any immobiliser work is quoted |
The matrix is a route to a finding and each vehicle is tested on its own evidence. A key that tests as sound but is no longer paired to the vehicle is put right through car key programming, a service with its own page.
Four Places an Immobiliser Fault Sits
Four parts make up a factory immobiliser, and a diagnosis ends when the fault is placed in one of them.
- The key transponder. A chip in the head of the key carries the code the vehicle recognises. Impact, water and age damage it, and a damaged chip gives a weak answer or none.
- The reader coil. A coil around the ignition lock, or behind the start button area on a push button start car, powers the chip and reads its answer. It is also called the antenna ring.
- The immobiliser module. The unit that compares the answer with the keys it holds in memory. Depending on the manufacturer it is a separate unit or part of the instrument cluster, the body control unit or the engine control unit.
- The wiring and the power supply. Connectors, fuses and battery voltage carry the signal between the other three. A corroded connector or low voltage stops a sound key and a sound module from talking.
The repair follows the part. Its aim is a factory immobiliser that works as the manufacturer fitted it, with every working key still recognised.
The Diagnostic Visit From Call to Tested Start
Five steps take an immobiliser fault from the phone call to an engine that starts.
- Call Matt on 0116 442 2084 with the make, model, year and registration, and say what the dashboard shows and how the spare key behaves. A quote is agreed before work begins.
- Matt arrives at the vehicle, at home, at work or at the roadside, and tests the battery voltage and each key you hold.
- The immobiliser fault codes and live data are read, and the reader coil signal is checked at the ignition or the start button.
- Matt shows you which part the evidence points to and agrees the repair with you before it starts. Where the repair involves key programming, identity and authority to request the work are checked.
- A repair that the vehicle supports at the roadside is carried out there, and the engine is started with each key, with you present.
Where a fault calls for workshop work, Matt explains the finding and the evidence behind it, so the next step for the vehicle starts from a known cause.
An immobiliser fault in Leicester is tested where the car stands, with the quote agreed first.
Call Matt on 0116 442 2084
Matt East Diagnoses Every Immobiliser Fault Himself
Matt East attends each immobiliser fault in person and carries out the testing himself. His locksmith training dates from 2011 and his automotive work from 2019, with more than 1,000 jobs completed.
For immobiliser diagnostic work Matt uses Advanced Diagnostics, Abrites and Autel equipment, with ODIS for supported Volkswagen Group work and JLR Topix for supported Jaguar Land Rover work. Inta-Lock is SERMI accredited, NCFE qualified and a member of the NNAL.
- SERMI Accredited
- NCFE Qualified
- NNAL Member
- Enhanced DBS Checked
- Insured to £5 Million
What the Immobiliser Repair Quote Depends On
Three things decide the quote for an immobiliser fault, and the figure is agreed before work begins.
- The part that has failed. A key, a reader coil, a module and a wiring fault are four different amounts of work.
- The make and the model year. Manufacturers build the immobiliser into different units and protect it in different ways.
- Whether keys are programmed afterwards. Some repairs end with the existing keys working as before, and others end with keys programmed to the vehicle again.
No price list is published for immobiliser work, because the fault is not known until the vehicle is tested. The charge for the diagnosis itself is confirmed on the call.
Immobiliser Diagnostics at the Vehicle Across Leicester
An immobiliser fault leaves the car where it stopped, so the diagnosis takes place on that driveway, street or car park. Matt is with you within the hour in Leicester, and the same day across Leicestershire.
Leicester AreasView All Areas We CoverInta-Lock Rated 4.9 by Leicester Drivers
Inta-Lock holds 4.9 out of 5 from 51 Google reviews on the Leicester listing, and the reviews are shown below.
View all Google reviews
Immobiliser Faults and the Faults Beside Them
Five neighbouring situations look like an immobiliser fault from the driver seat, and each one leads somewhere different.
A Factory Immobiliser Compared With Autowatch Ghost 2
Comparison. Both prevent the engine from starting until the vehicle receives the authorisation it expects.
Differences. The factory immobiliser is built in by the manufacturer and recognises the coded key. Autowatch Ghost 2 is an aftermarket immobiliser added to the vehicle afterwards, and it asks for its own disarm sequence.
Similarities. Both work without any action from the driver beyond the normal start routine, and a vehicle fitted with the second still relies on the first.
Effects. A factory immobiliser fault is diagnosed and repaired on this page. A driver who wants a second layer of protection on a working car reads about Autowatch Ghost 2 fitting.
An Immobiliser Fault and an Ignition Fault
An ignition fault is in the lock or the switch. The key does not turn, sticks part way, or turns without the dashboard coming on.
An immobiliser fault leaves the lock working. The key turns, the dashboard lights, and the engine is refused. The two are confused because the reader coil sits around the ignition lock on many cars. A key that does not turn belongs with ignition repair.
A Dead Remote and a Rejected Key
The buttons on a key and the chip that starts the engine are separate circuits. The remote runs from the fob battery. On a key that turns in an ignition lock, the transponder chip draws its power from the reader coil.
A key whose buttons have stopped while the engine still starts has a remote fault, which is the work of key fob repair. A key whose buttons work while the engine is refused has a transponder or immobiliser fault.
A Flat Vehicle Battery and an Immobiliser Fault
A flat vehicle battery and an immobiliser fault both leave a car that does not start, and low voltage lights the security symbol on some vehicles.
The difference shows in the crank. A weak battery turns the engine slowly or clicks, and the dashboard dims. An immobiliser fault leaves a healthy crank and a bright dashboard. Battery voltage is the first reading Matt takes for that reason.
A Mobile Diagnosis Compared With a Recovery
Comparison. Both lead to the same question, which part of the immobiliser has failed.
Differences. A mobile diagnosis tests the car where it stopped. A recovery moves the car to a workshop first, and the testing begins after it arrives.
Similarities. The same fault codes, live data and key tests apply in both places.
Effects. A fault in a key or its programming ends at the vehicle with no transport to arrange. A car parked outside a house in Thurnby Lodge and Netherhall is tested on that street.
Frequently Asked Questions
How do I know the immobiliser is the fault?
An immobiliser fault shows as a security light that flashes or stays lit with the ignition on, while the engine cranks without firing or starts and stops.
A spare key that starts the car places the fault in the first key. A slow crank and a dim dashboard point to the vehicle battery instead.
What does a flashing immobiliser light mean?
A security light that keeps flashing after the ignition is switched on means the vehicle has not accepted the key.
The same light flashing slowly on a locked, parked car is normal on many cars. It shows that the immobiliser is armed.
Is a spare key that also fails a sign of a vehicle fault?
Yes. Two keys rejected in the same way point to the vehicle side of the immobiliser, the reader coil, the wiring or the module, more than to either key.
Both keys are still tested, because two keys of the same age share the same wear.
Does disconnecting the battery reset the immobiliser?
No. Disconnecting the vehicle battery does not repair a fault in the key, the reader coil or the immobiliser module.
The key data is held in memory that keeps its contents without power, so the same fault returns when the battery is connected again.
Can an immobiliser fault be repaired at my home in Leicester?
Yes. The diagnosis takes place at the vehicle, at home, at work or at the roadside, and a repair that the vehicle supports there is carried out on the same visit.
Where a fault calls for workshop work, the finding and the evidence are explained to you first.
How much does immobiliser repair cost in Leicester?
The cost of an immobiliser repair depends on which part has failed, and a quote is agreed before work begins.
No price list is published. The make, the model year and whether keys are programmed afterwards all change the work involved.
What do I have ready when I call about an immobiliser fault?
Have the make, model, year and registration ready, along with what the dashboard shows and whether a spare key behaves the same way.
Where the repair involves key programming, identity and authority to request the work are checked. The V5C vehicle registration certificate and photo identification are common examples, and what applies is confirmed on the call.
Call Matt with the make, the model and what the dashboard shows.