Mobile Motor vehicle repairs
Auto electrical & specialist services
Tel: 07703 558610

Car, Van or Truck  breakdown ?   Mobile workshop vehicle diagnostic and vehicle repair callout services around Shrewsbury, Telford, Shropshire and Mid Wales areas *subject to availability

Common causes of vehicle breakdown:

Fuel System faults:

Fuel Type:

Petrol car refuelled with diesel
Diesel car fuel tank filled up with petrol.
When a vehicle is refuelled  with the wrong type of fuel at a service station several problems may result:

1.The contaminated mixed fuel becomes a hazardous waste so needs proper recovery and disposal

2.The engine will possibly either not start or run erratically

3.Further engine damage may occur.
The Fuel injection system  fitted to diesel engines can be susceptible to damage caused by accidentally filling with petrol

Fuel Quantity

Vehicle has run out of fuel.
Fuel guage faulty
Low fuel warning light (if fitted) does'nt work
Low pressure fuel pump has failed
Fuel injection system fault.

Fuel Quality

Water in fuel.
Incorrect fuel type when refuelled.

Fuel injection system breakdown

Possible Cause:
Fuel filter blocked
Fuel Injectors fault
Wrong fuel
Incorrect fuel system calibration
Fuel pump timing
No signal from crankshaft position sensor
Fuel pump failure
Fuel pump relay
Sensor or actuator faults
Wiring defect
Electronic control unit failure
Black smoke from exhaust

Electronic ignition system breakdown

No ignition spark at sparkplugs
Cylinder misfire
Difficult starting

Possible Cause:
Broken wiring
electronic sensor faulty
blown fuse
wiring short
defective components, HT leads, Coil pack, Ignition switch failed, Crank sensor failure, Camshaft sensor failure, wiring.

Lights not working or dim

Possible cause:
Blown bulbs
Blown fuse

If an electrical  fuse keeps blowing on your vehicle - Do not replace with a larger fuse as this may lead to further circuit problems.

Electrical wiring circuit
Switch faulty
Control module fault

If an electrical  fuse keeps blowing on your vehicle - Do not replace with a larger fuse as this may lead to further circuit problems.

Further causes may be failed component, wiring short circuit,

Breakdown due to Battery, Charging System, or Starter Motor

Flat battery

Battery at end of life
Battery electrolyte level low. The electrolyte level of the battery should be checked in accordance with the manufacturers instructions.
Wiring fault causing current drain
Alternator / Generator / Dynamo charging system fault
Battery discharhed due to driver error eg lights left switched on.

Battery test
A battery capacity test identifies the ability of the battery to store energy for supplying the high current required to start your vehicle from cold. A battery on a 12 volt system should be recharged when the open circuit voltage drops to below 12.2volts. If a battery is to be recharged off the vehicle it should be done in a well ventilated area away from sources of ignition.

On a functional charging system the vehicle battery is recharged by the alternator during operation.

Battery Warranty

Warranty period for vehicle batteries is usually one, two, three, or four years, and the longer warranty being a slightly higher price.

Battery Specification

Vehicle manufacturers specify design and capacity of vehicle battery so it is important to select the correct size and type.
It is essential that the vehicle battery is properly secured when fitted.

Symptoms of a defective battery are no ignition lights coming on , vehicle not starting ,charge warning light staying on with the engine running. Battery faults can also be caused by defects in the vehicle charging system, or by wiring & component faults causing current drain. Battery voltage which is too low or too high due to defective charging system can have knock on effects on vehicle computer controlled systems including engine management and automatic transmission.


Alternator faults
The purpose of the alternator is to provide electrical power for vehicle equipment and to supply energy to recharge the vehicle battery.
An alternator not charging can be caused by:
defective wiring
loose mountings
loose or broken drivebelt possibly caused by tensioner failure.
worn or failed components within the alternator.
The alternator can be tested to a certain extent on the vehicle or removed for bench testing.
Alternator output data may be monitored by the vehicle engine control unit (ECU).

Alternator failure may result in battery charge warning light illumination and eventually a discharged battery

Starter Motor

Defects in starter motor operation can be caused by component failure within the unit or external component failure with items such as battery , wiring, connections, ignition switch, immobiliser. etc

Cambelt or Cam timing

Timing belt.
The timing belt synchronises engine component operation of Crankshaft, Valves and camshafts . Sometimes fuelling equipment also. The cam timing belt is a rubber toothed belt running on sprockets and pulleys. Failure of the cam timing belt usually has disastrous effects for the rest of the engine with pistons colliding with valves. The cam timing belt and idler pulleys should be renewed as part of scheduled vehicle servicing. Engine oil leakage onto the cam timing belt can also encourage early timing belt failure.

Possible breakdown causes include broken belt, teeth missing from belt, idler bearing failure. Failure of cambelt usually results in major engine damage.

Clutch Problems

Broken or snapped clutch cable, clutch not clearing, clutch hydraulic fluid leaking, clutch plates worn out or damaged, oil leak onto clutch causing it to slip.

Wheels and tyres:

Puncture causing flat tyre , Loss of seal between tyre bead and wheel rim, Leaking valve.

Electric windows

Window stuck open, broken wiring, electric window motor failure, switch fault, control module fault, wiring problem.


keys locked in vehicle.
Car keys lost
Incorrect Key : Key code not matched to immobiliser :
key code not read : Transponder system fault
Central locking not working
Central locking switches, wiring or control module fault.

Suspension fault

Roadspring broken or fractured, radius or control arm bushes, shock absorber broken, shock absorber bushes worn out,shock absorber fluid leaks. Component insecure


Power steering oil leak from reservoir pump or hoses, heavy steering, low tyre pressure, steering rack damage or wear, electric power steering failure, alternator failure, auxiliary drive belt condition. Steering track rod ends.


Detached, fractured or broken pipe, mountings adrift. Broken exhaust manifold studs, Lambda sensor faults, Emissions failure, Catalytic converter or diesel particulate filter blocked, dpf sensor faulty, wiring to dpf sensor faulty,

Engine Lubrication and Cooling

Engine Oil

Engine Oil is pumped around the engine to provide lubrication of moving metal components so they don't seize up.
Engine oil level should be maintained using the correct grade of oil to manufacturers specification.
Engine oil & filter change is carried out as part of scheduled servicing.
Too little engine oil can result in component failure due to lack of lubrication.
Too much engine oil can cause the running engine to suck up the oil, and use it as a fuel, then accelerate to destruction.
Used engine oil is a hazardous waste. Waste engine oil requires safe handling and disposal.
Oil spills may be contained using absorbent granules or an oil spill kit.

Low oil level , engine oil leak, Loss of oil pressure due to wear or oil pump failure. Symptoms : Excessive exhaust emissions, Engine oil warning light on, Low oil pressure registered on guage. Effect : Can lead to seized engine.

Cooling System

Engine cooling system
Failure of the cooling system can be caused by leaks due to perishing of rubber hoses or failure / corrosion of components, or gasket failure. Signs are engine overheating, coolant leaks, engine not reaching operating temperature, failure of thermostats, fans, etc.
Loss of engine coolant can result in the engine overheating and a seized engine or cylinder head / engine block damage.

Possible Problem: Overheating :
Possible causes : Low coolant level,  leaking hoses, oil in coolant, oil cooler failure, head gasket failure, thermostat stuck, overheating, coolant temperature sensor or circuit fault, fan motor failure, blocked radiator, water pump failure, drive belt failure. Blocked air conditioning condenser.

Possible Problem: Operating temperature too low , Excess fuel consumption, Difficult starting.

Possible causes : Low coolant level, Thermostat missing or stuck open, Coolant temperature sensor faulty, Wiring fault.

Braking System

Possible Problem: Overheating :
Possible causes : Brake calipers or wheel cylinder sticking master cylinder sticking ,  handbrake cable defective or incorrect adjustment. Disc or drum surfaces scored.
Possible Problem: Efficiency : Pulls to one side under braking, hydraulic system fluid loss, pressure loss.

Possible Problem: ABS fault: damaged wiring, faulty sensor, solenoids, modulator, switches. reluctor, control module

Immobiliser breakdown

Possible problems: Loss of coded key transponder signal, Immobiliser control unit fault, wiring

Preventative Maintenance Inspection & Regular Servicing

While some breakdowns are unforeseeable having a preventative maintenance inspection can often identify potential breakdown faults before they occur.
For example loose wiring which is not secured can chaff and rub against sharp edges, wearing away the insulation ready to cause a short circuit and a breakdown.

Preventative maintenance inspections to manufacturers specification will ensure your vehicle safety, life, and asset resale value.
The annual vehicle MoT test is a form of Preventative Maintenance Inspection to identify components corroded, or worn or insecure that may cause a breakdown or threat to other road users.
However there are many items not covered by the annual MoT inspection and a pass can mean that a vehicle has only met a minimum standard of roadworthiness. The credit crunch is affecting many people and an attempt is often made to reduce  costs  by extending service intervals.There are many vehicle items requiring regular maintenance such as brakes, axles, gearboxes, lights ,etc.

Refer to your vehicle manufacturers handbook for further information.

Vehicle  Breakdown  Assistance

Roadside Breakdown Health & Safety

Awareness of health and safety is very important in the event of a roadside breakdown

Do not place yourself or others at risk.
Where recovery is likely to obstruct flow of traffic inform the police.

  • If possible park straight ahead with your vehicle wheels pointing to a safe impact area (usually the left on uk roads),this is in case another vehicle crashes into the rear of your vehicle whilst it is broken down.
  • If you need to exit from your vehicle do so from the safe side and not into the traffic flow.
  • If your vehicle has been repaired or becomes mobile take care when rejoining moving traffic.
  • Be aware that intermittent faults which may have occurred then apparently disappeared may reoccur without notice.Have your vehicle checked out as soon as possible.
  • Only specialist vehicles and trained technicians should attempt to recover vehicles from motorway networks.

  • This is just a brief overview and will be added to as spare time permits.

    A few things worth carrying in your vehicle in case of roadside breakdown:
    * Mobile cellular phone *
    * Contact details of a breakdown organisation & relatives *
    * A blanket *
    * Reflective Warning Triangle *
    * High Viz jacket / vest *
    * Flashlight *
    * Tow rope *
    * Battery booster cables *
    * Wheelbrace *
    * Jack *
    * A Road Map so you can specify your location in case of breakdown in unfamiliar areas *
    * Spare engine oil *
    * Spare water *
    * Spare bulb kit *

    We are pleased to help with enquiries relating to vehicle electrical or mechanical maintenance and repair in and around Shrewsbury, Shropshire areas.

    Autoelectrics Mobile Product Services
    Watermill View
    SY21 8EG
    Mobile: 07703 558610

    Web page last update 12th March 2023