Why Your BYD Song Plus's Check Engine Light Flickers and Idles Rough – What to Check First

Understanding the Symptoms

A flickering check engine light combined with a rough idle on your BYD Song Plus usually points to a misfire or an air-fuel mixture problem. The flickering means the engine computer is detecting a severe enough issue that could damage the catalytic converter if ignored. The rough idle often gets worse when you're at a stoplight or in Park.

Likely Causes and What to Check First

Start with the easiest and most common culprits:

• Spark plugs and ignition coils – Worn plugs or a failing coil cause intermittent misfires. Check for any cylinder-specific misfire codes.
• Vacuum leaks – A cracked hose or gasket lets in unmetered air, leaning out the mixture. Listen for hissing around the intake manifold.
• Mass airflow (MAF) sensor – A dirty MAF sends incorrect readings, making the engine run rough. Clean it with MAF cleaner.
• Throttle body or idle air control valve – Carbon buildup can stick the throttle plate or bypass valve, causing erratic idle.
• Oxygen sensors – A failing O2 sensor can cause the engine to run rich or lean and trigger the check engine light.

Is It Safe to Keep Driving?

If the light is flickering and you feel shuddering, it's best to avoid heavy loads and long trips until you diagnose the misfire. Repeated misfires can overheat and ruin the catalytic converter, leading to an expensive repair. Drive gently to a shop or check the basics (tighten fuel cap, inspect obvious wires) – but don't ignore it.

This material is AI-generated and for informational purposes only — it does not replace an in-person diagnosis by a qualified mechanic.