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ECU and Immobiliser Fault Diagnostics in St Albans
Herts Car Keys diagnoses immobiliser faults in St Albans at the vehicle. Darius traces why a car no longer recognises its key, from the chip in the key to the immobiliser and its link with the engine ECU. The typical response is around 30 minutes, and the exact price is confirmed before work starts.
- 30 minTypical response
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- Around 30 minutestypical response
What ECU and Immobiliser Diagnostics Covers
The immobiliser is the security system that stops the engine from starting without a recognised key. It reads the chip in the key and passes the result to the engine ECU, the computer that controls the engine. Immobiliser fault diagnostics is the work that finds where that chain has failed.
The service covers the key, the immobiliser and the pairing between them. General engine faults and wider vehicle diagnostics belong to a garage.
The handshake takes a fraction of a second. When the key enters the ignition or the start button is pressed, an antenna ring around the barrel or in the cabin powers the chip in the key. The chip answers with a code. The immobiliser unit checks the code against its list and tells the engine ECU to allow fuel and ignition. A break at any point in that chain leaves the engine turning over with no start, or stops it a second after it fires.
Signs of an Immobiliser Fault
An immobiliser fault shows in five ways.
- The engine turns over and does not start.
- The engine starts and cuts out after a second or two.
- A key or padlock light flashes on the dashboard.
- The dashboard shows a key not recognised message.
- The car starts with one key and not with the other.
Immobiliser Fault, Flat Key Battery or Flat Car Battery
Three faults look alike from the driving seat and are told apart in a minute. A flat car battery gives a click or a slow turn of the starter and dim dashboard lights. A flat key battery stops the remote and the keyless start, while the engine still starts with the key held against the start button. An immobiliser fault lets the starter turn at full speed and the dashboard light up, yet the engine does not fire or cuts out after a second.
Darius checks the car battery and the key battery first, because a driver who has ruled both out saves the cost of a diagnostic visit for a cell.
Immobiliser Faults Herts Car Keys Diagnoses
Immobiliser faults fall into three groups.
Key Not Recognised
The chip in the key is damaged, or the key has lost its pairing with the vehicle. The fault is fixed through car key programming or with a new key.
Immobiliser System Faults
The reader ring around the ignition, the wiring or the immobiliser unit has failed, so no key is read.
Electric Steering Lock Faults
The electric steering lock on some vehicles fails and blocks the start, although the key itself is sound.
Immobiliser Diagnostics in 4 Steps
Darius traces an immobiliser fault in four steps at the vehicle.
Read the fault codes from the immobiliser and the engine ECU through the diagnostic port.
Test the chip in each key and compare it with the keys the immobiliser holds.
Test the antenna ring and its wiring while a key is in the ignition.
Pair the key again, program a new key or replace the failed part, then test the start.
What Affects the Cost of Immobiliser Diagnostics
The cost of immobiliser diagnostics depends on the make, on the model year and on the fault that is found. A key that is only paired again costs less than a failed immobiliser part. Darius confirms the price of the diagnostic visit before he sets off, and the price of any repair before that work starts.
A fault in the key is the cheapest fix, because the key is paired again or a new key is programmed. A fault in the antenna ring or the wiring costs more, because a part is replaced. An electric steering lock fault on a vehicle that supports an emulator sits between the two. Darius names the fault and the price before the repair starts.
Immobiliser Repair at the Vehicle
A car with an immobiliser fault does not start, so a mobile visit removes the need for a recovery truck. The typical response to St Albans is around 30 minutes.
The service runs 24 hours a day, 7 days a week. It covers St Albans city centre, Fleetville, Marshalswick, Sandridge, Colney Heath and Bricket Wood, and towns within around 15 miles of Welwyn Garden City.
Darius Traces Each Immobiliser Fault
Darius is the owner of Herts Car Keys and the locksmith on every immobiliser fault job. He has six years in the trade and has completed over 7,000 car key and lockout jobs.
SERMI Approved, DBS Checked and Fully Insured
Herts Car Keys holds approval under the SERMI scheme, which gives an independent locksmith a recognised route to manufacturer security data for the makes that take part. Darius holds a DBS check and carries full insurance for work on customer vehicles.
Named Programming Tools on the Van
Darius programs keys with named tools that include Smart Pro, Autel and Lonsdor. Each tool covers different makes, so the key is programmed with the tool that supports that system.
Recent Immobiliser Fault Fixed by Herts Car Keys
The electric steering lock failed on a 2013 Mercedes C-Class. Darius programmed an emulator and the fault was solved.
Call Herts Car Keys About an Immobiliser Fault
A car that does not recognise its key in St Albans is checked at any hour. Call 07308 888825 or send a WhatsApp message with the make, the model, the year and the warning on the dashboard.
Guide to the Nissan Key Warning Light
One guide sits next to immobiliser fault diagnostics.
The guide to the Nissan flashing red key icon explains one common immobiliser warning light.
Frequently Asked Questions
Call 07308 888825What are the signs of an immobiliser problem?
The engine turns over and does not start, the engine cuts out after a second or two, or a key light flashes on the dashboard.
Can you repair ECU faults on-site?
Herts Car Keys deals with faults between the key, the immobiliser and the engine ECU at the vehicle. General engine ECU repair is a separate trade and is not part of the service.
Do you work with all car makes and models?
Herts Car Keys works on most car makes. Tesla is not covered at present, and Mercedes replacement key work is limited to supported models up to 2015.
Can you reprogram keys if the immobiliser is not working?
The fault is found first. A key is programmed again once the immobiliser reads keys, because a key cannot be paired with a system that is not working.
Is ECU and immobiliser diagnostics expensive?
The cost depends on the make, on the model year and on the fault that is found. The price of the visit is confirmed before Darius sets off.
Do you offer 24/7 ECU and immobiliser services?
Yes. Herts Car Keys is open 24 hours a day, 7 days a week, including nights and weekends.
Will I need to tow my car to you?
No. Herts Car Keys is a mobile service, and the fault is normally traced where the vehicle stands.
How much does it cost to fix an immobiliser?
The cost depends on the fault. A key that is paired again costs less than a failed immobiliser part, and the exact price is confirmed before work starts.
Does a flat key battery cause an immobiliser fault?
A flat cell stops the remote and the keyless functions. On most keys the chip still works when the key is held against the start button or the ignition. A car key battery replacement rules the cell out.
Can a car be driven with an immobiliser fault?
No. The immobiliser stops the engine from running, so the car stays where it is until the fault is traced and the key or the part is fixed.
Does an immobiliser fault drain the car battery?
A fault in the immobiliser unit or its wiring drains the battery on some vehicles, because a module stays awake. Repeated attempts to start the car drain it as well, so Darius checks the car battery during the visit.