Key Takeaways

• The 2003 Mazda Protege utilizes the 2.0L FS-DE engine, which is generally robust but susceptible to head gasket failure under overheating conditions.
• Primary symptoms include white exhaust smoke, coolant loss without visible leaks, and oil contamination (mayonnaise-like substance).
• Professional repair costs typically range from $1,800 to $2,500, depending on labor rates and cylinder head machining requirements.
• Immediate cessation of driving is recommended upon confirmation of failure to prevent catastrophic engine warping.

The 2003 Mazda Protege remains a respected vehicle in the compact sedan segment, largely due to the reliability of its 2.0L FS-DE inline-four engine. However, like many aluminum-head engines of this era, the 2003 Mazda Protege head gasket is a critical failure point that owners must monitor. This analysis provides a technical deep-dive into the failure modes, diagnostic data, and economic considerations for repair