Diagnostics & Fault Finding

Modern commercial vehicles are as much computer systems as they are mechanical machines. An HGV today can carry upwards of 50 electronic control units (ECUs) managing everything from engine management and emissions aftertreatment to gearbox operation, air suspension, and traction control. When something goes wrong, finding the root cause quickly — rather than replacing parts on guesswork — is the difference between a half-day repair and a vehicle off the road for days.

HFG Commercials is equipped with professional OEM-level and multi-brand diagnostic tooling, giving us fast, accurate access to fault codes, live data, and system parameters across every commercial vehicle we work on.

Van Diagnostics — MAN TGE and All Makes

The MAN TGE uses Volkswagen Group architecture — which means its electronic systems are tightly integrated and require proper diagnostic equipment to interrogate correctly. Warning lights, DPF regeneration faults, AdBlue and SCR errors, engine management issues, and electrical faults all need accurate reading before any repair work begins.

As a MAN Authorised Repair Centre, we have access to manufacturer-level diagnostic capability for MAN TGE vehicles. This allows us to read and interpret fault codes across every ECU — not just the engine — view live data streams including fuelling, temperature, pressure, and sensor outputs, perform active component tests, carry out software adaptations and parameter updates where required, and diagnose AdBlue and SCR system faults including dosing pump operation, NOx sensor readings, and catalyst condition. DPF issues — blockage, failed regeneration, differential pressure faults — are diagnosed accurately before any parts are recommended.

For all other makes of light commercial vehicle we use TEXA multi-brand diagnostic software — one of the most comprehensive systems available in the UK for commercial vehicle coverage.

HGV Diagnostics — MAN Trucks and All Makes

HGV fault finding is particularly complex. A single warning light may involve the interaction of two or three ECUs, a sensor reading correctly but interpreting data incorrectly, or a CAN bus communication fault entirely separate from the system showing the error. Getting this right the first time requires both the right tools and genuine experience with how commercial vehicle systems interact.

For MAN Trucks, we use MAN CATS III — the same diagnostic software used by authorised MAN dealers. This gives us full access to engine ECU and emissions system diagnostics (AdBlue/SCR, EGR, DPF), TipMatic gearbox fault codes and adaptation, EBS (Electronic Braking System) diagnosis, ECAS air suspension fault finding, retarder, intarder, and exhaust brake systems, tachograph and telematics integration, and software update capability where permitted.

For all other HGV makes — Volvo, DAF, Mercedes-Benz, Scania, Iveco, Renault Trucks — we use TEXA Truck diagnostic software, which delivers professional-grade multi-system coverage across all major European manufacturers.

Clear explanations, not jargon

When we find a fault, we explain what the system does, what’s wrong with it, and what happens if it’s left. We don’t issue vague ‘further investigation required’ reports or recommend parts on guesswork. You get a clear, honest assessment of what your vehicle needs and why — then the decision is yours.