Fuel trim data tells you what the engine control module is doing to keep the air-fuel ratio correct — and when the corrections get large enough, they tell you exactly what kind of fault is causing the problem. A technician who can read fuel trims correctly can walk up to a running engine, pull live […]
A misfire code tells you combustion failed in a specific cylinder — it does not tell you why. The cause could be ignition, fuel, mechanical, or a wiring fault, and each one requires a different repair. The fastest path to the right answer is a structured approach using misfire counters, live data, and a logical […]
A fuel injector circuit code or cylinder-specific misfire points you toward the injector — but the injector is rarely the first thing to test. The same codes are produced by a missing power supply, a failed PCM driver, a broken wire, or a bad ground. Testing the circuit before condemning the injector saves the cost […]
Ignition coil failures are one of the most common causes of misfire codes, but they are also one of the most frequently misdiagnosed. A coil that tests fine on a resistance check can still break down under the voltage stress of a loaded engine, particularly when hot. A coil that appears suspect based on a […]
Throttle Position Sensor (TPS) faults — including those on electronic throttle bodies (ETB, drive-by-wire) — trigger codes like P0120–P0124, P0220–P0229, P2135 (TPS1/TPS2 correlation), and P2138 (APP/TPS mismatch), often accompanied by reduced power or limp mode. Modern throttle systems use two redundant signals for safety, so a single fault can shut down normal throttle response immediately. […]