Glossary

A belt-driven generator that charges the battery and powers the vehicle's electrical system while the engine is running.

An exhaust component that uses a precious-metal catalyst to convert harmful combustion byproducts into less harmful gases before they reach the tailpipe.

A standardized alphanumeric code (e.g. P0299) that a vehicle's computer sets when it detects a fault, pointing a technician toward the affected system and circuit.

The onboard computer that manages fuel injection, ignition timing, and dozens of other engine functions using real-time input from the vehicle's sensors.

The dashboard warning light — usually shaped like an engine outline — that illuminates when the onboard computer detects and stores a diagnostic trouble code.

An engine cylinder that fails to combust properly — from a weak spark, bad fuel delivery, or low compression — causing a rough idle, hesitation, or a flashing check engine light.

The standardized on-board diagnostics system, mandatory on US-market vehicles since 1996, that reports diagnostic trouble codes and live sensor data through a common 16-pin connector.

A metal chain that keeps the crankshaft and camshaft(s) rotating in sync so intake/exhaust valves open and close at the correct point in the engine cycle.

A rotational force, measured in newton-meters or foot-pounds — the spec a factory manual gives for how tight a fastener (like a wheel lug or head bolt) must be turned.

A turbine-driven forced-induction device that uses exhaust gas energy to compress intake air, letting a smaller engine produce more power.