Diagnostics
Diagnostic procedures and troubleshooting guides
GDI Carbon Buildup: Diagnosis, Walnut Blasting, and Prevention
Gasoline Direct Injection engines are taking over, and carbon buildup on intake valves is a ticking time bomb. Here is everything you need to know about diagnosing it, cleaning it, and preventing it.
Diagnosing Intermittent Electrical Problems: The Hardest Job in the Shop
Intermittent electrical faults are the white whale of auto repair. The problem comes and goes, never acts up on your test drive, and makes you question your career choice. Here is how to catch them.
CAN Bus Communication Fault Diagnosis: U-Codes and Dead Modules
U-codes are the most intimidating DTCs for a lot of techs. When modules stop talking to each other, here is how to figure out which one went silent and why.
How to Diagnose EVAP System Leaks: P0440, P0442, P0456 Decoded
EVAP codes are some of the most common check engine lights and some of the most annoying to diagnose. Here is how to actually find the leak instead of guessing at parts.
P0300 Random Misfire Diagnosis: The Complete Decision Tree
P0300 is one of the most frustrating codes because it points everywhere and nowhere at once. Here is a systematic approach to diagnosing random and multiple cylinder misfires without throwing parts at the problem.
Why Is This Car Eating Oil? (A Diagnosis Guide)
Customer adds a quart every 2 weeks. Some manufacturers say thats normal. Is it tho?
That Grinding Noise Isnt Always What You Think
Customer says brakes are grinding. Could be pads, could be something else entierly. Lets figure it out.
Finding Parasitic Draws Without Going Crazy
Customer says battery keeps dying. Time to find whats draining it. Heres the process.
Voltage Drop Testing: The Skill That Changed Everthing
If you only learn one electrical diagnostic technique make it this one. Seriously.
No Start Diagnosis Without Losing Your Mind
Customer says car wont start. Could be 50 different things. Heres how to narrow it down fast.
What to Actually Tell Customers About Check Engine Lights
Getting tired of the "but its just a light" conversation? Heres how I explane it.
Best $300 I Ever Spent: My Smoke Machine
If you dont have a smoke machine yet youre wasting hours of your life. Not even exagerating.
Fuel Trims Finally Explained (Without the BS)
Everyone talks about fuel trims but nobody actually explains them in plain english. Let me fix that.
Stop Guessing and Start Actually Diagnosing
I see it all the time - techs throwing parts at cars hoping something sticks. Heres how to actually find whats wrong.
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