Diagnostics
Engine Diagnostics
Engine faults are usually a chain of events rather than a single broken part. We test fuelling, ignition, air, compression and control signals to find where the chain breaks.
Engine running badly?
Symptoms we investigate
- Engine management light with or without a noticeable fault
- Misfire under load, at idle or when cold
- Loss of power, flat spots and limp mode
- Excessive fuel consumption
- Rough idle, stalling or hunting
- Knocking, ticking or rattling noises
- Smoke from the exhaust
- Engine cranking but not starting
What we test
- Stored fault codes and live sensor data
- Fuel delivery and pressure where relevant
- Ignition components on petrol engines
- Air intake, boost and vacuum leaks
- Emissions and after-treatment readings
- Mechanical condition, including compression and timing where indicated
Honest outcomes
Some engine faults turn out to be inexpensive — a sensor, a hose, a coil or a connector. Others reveal wear that needs more involved work. Either way we explain what has been found, what it means for the vehicle and what the realistic options are before anything is ordered.
Frequently asked questions
Warning light on?
Our work
Recent jobs from our workshop
Photographs taken during work carried out at our Iver workshop.
Piston removed during an engine strip, showing carbon build-up
Inlet manifold off — carbon build-up in the runners
Carbon-choked inlet port found during diagnosis
Soot in the inlet ports after high-mileage diesel use
Advice
Helpful reading on this fault
Your engine management light is on — what now?A steady light and a flashing light mean very different things. Here is how to tell whether to book in or stop driving.Read more How to reset an engine management light — and when you shouldn'tClearing the code turns the light off. It does not fix what turned it on — and it can hide a fault that is still costing you.Read more Will an engine management light fail an MOT?An illuminated engine management light is a straight MOT fail — and clearing it the night before does not get you past the test.Read more
Symptoms
Symptoms that often lead to this repair
Look up what your car is doing and read what it commonly means.
Battery warning light on while drivingThe red battery symbol is a charging-system warning. The engine is normally running on stored battery power only, which is limited.Read more Engine management light flashingA steady amber light and a flashing one are very different. Flashing normally indicates a misfire severe enough to risk expensive damage.Read more Rattling noise on start-up that goes awayA short rattle from cold that clears once oil pressure builds is a common early warning. Ignoring it can turn a chain job into an engine job.Read more Whining noise when acceleratingThe useful question is whether the whine follows engine revs or road speed, because that separates belt and turbo noises from gearbox and differential noises.Read more Car judders when pulling awayJudder can be transmission or engine related. Whether it also happens while driving at steady speed helps separate the two.Read more White smoke from the exhaustColour, smell and whether the smoke clears once warm are what separate normal condensation from a coolant or fuelling problem.Read more Blue smoke from the exhaustBlue smoke points at oil reaching the combustion chamber or exhaust. When it appears — start-up, overrun or under boost — narrows the cause.Read more Car losing power when acceleratingLoss of power is either a fuelling, air or protection issue. Live data under load is what separates them rather than guesswork.Read more Car cutting out while drivingIntermittent cut-outs are among the most important faults to record properly, because the evidence disappears the moment the engine restarts.Read more Engine misfire: symptoms and common causesA misfire means a cylinder is not contributing properly. It is either fuel, spark or compression on that cylinder — and identifying which comes before parts.Read more Car shaking or vibrating at idleIdle is where small faults show up most, because the engine has no load to smooth them out.Read more Head gasket failure symptomsHead gasket failure is often suspected and less often confirmed. Testing first matters, because several cheaper faults produce similar symptoms.Read more Smell of petrol in or around the carFuel vapour is a fire risk, so a petrol smell is one of the few symptoms worth acting on the same day.Read more Airbag warning light onThe airbag light means the restraint system has logged a fault and may not deploy correctly, so it is worth reading properly rather than clearing.Read more Oil pressure warning light onOf all the dashboard lights, oil pressure is the one to take most seriously — running an engine without pressure can cause damage quickly.Read more Car jerking when acceleratingJerking under load usually means the engine is briefly not getting the fuel, air or spark it needs — live data while driving is the quickest route to the cause.Read more
Related
You may also need
Car Diagnostics & Fault Finding in IverA warning light tells you something has been detected — not what has failed. We diagnose the vehicle first so the repair that follows is the repair the car actually needs.Read more Engine Repairs in IverEngine faults are where guesswork gets expensive. We test, measure and read live data before anything is replaced.Read more Turbo ReplacementTurbo failure often has an underlying cause. Oil supply, restriction and boost control are checked first — otherwise the new turbo goes the same way as the old one.Read more Diesel DiagnosticsModern diesels combine high-pressure fuelling, turbocharging, exhaust gas recirculation and after-treatment. When one part of that system drifts, the symptoms usually show up somewhere else.Read more Car Won't Start?A car that will not start is not one fault — it is a shortlist. Working through that list in order is how you avoid buying parts you did not need.Read more
Talk to us about engine diagnostics
Based in Iver, covering West London, Berkshire and South Buckinghamshire. Send your registration and we will quote for your vehicle.