// DiagEdge Guides
Practical, no-fluff diagnostic walkthroughs — fault codes, live data, oscilloscope testing and the logic behind them. Written for techs who want to find the real cause, not just replace the part the code names.
What short-term and long-term fuel trims mean, what counts as normal, and how to read them at idle vs load to separate vacuum leaks, fuel delivery and MAF faults.
How to interpret low-side and high-side AC gauge readings to tell undercharge from overcharge, a weak compressor, or a condenser/airflow problem.
The difference between insufficient and excessive EGR flow codes, why carbon is usually to blame, and how to test EGR operation before replacing the valve.
What a lean code on one or both banks tells you, how to read fuel trims to separate a vacuum leak from a fuel delivery or MAF problem, and how to confirm it.
How to measure parasitic draw correctly, what counts as normal, letting modules sleep, and using the fuse voltage-drop method to find the circuit fast.
Why P0300 means a misfire across multiple cylinders, the common causes from vacuum leaks to fuel delivery, and how to use Mode 6 and fuel trims to pinpoint it.
A structured way to diagnose a dead CAN bus or a module that won't communicate: power and grounds, the 60-ohm resistance test, and isolating a shorted module.
What AC ripple on the charging system looks like on a scope, how to spot a failed diode, and why excessive ripple causes strange electrical and network faults.
Passive vs active vs forced DPF regeneration explained, the real reasons a regen fails, and how to diagnose the underlying cause instead of just clearing the light.
What P0420 really means, why it is rarely just a failed catalytic converter, and a step-by-step way to diagnose it before you spend money on a new cat.
AI-powered diagnostic guidance across six specialist modules. First month just A$1.
Start for A$1 today