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1997 Buick Lesabre Custom P0300 Code: Diagnosis and Solutions After Replacing All Ignition Components

Model: 1997 Buick Lesabre Custom Fault Code: P0300 Posted: 2011-03-23 18:44

I'm still struggling to resolve the P0300 code on my 1997 Buick Lesabre Custom. Despite replacing all ignition components—including spark plugs, wires, coil packs, ignition control module, crankshaft position sensor, the air cleaner-to-throttle body duct, and the O2 sensor located behind cylinder #6—each time I scan the vehicle, the P0300 code persists. This is becoming a major issue as I'm now spending over $100 per tank just to keep the car running. I need clear guidance on what else could be causing this misfire and how to properly diagnose it without further wasting money on unnecessary parts.

Related fault codes

P0300

Comments (2)

Anonymous 2011-03-24 05:01

Could a stuck open EGR valve be contributing to the P0300 code? It's worth checking, especially in older Buick Lesabre models with known EGR issues.

Anonymous 2011-03-24 16:41

Before replacing more parts, it's essential to first identify which cylinders are misfiring. Then determine whether the issue stems from fuel delivery, ignition, or mechanical problems. Key diagnostics include checking fuel pressure, injector pulse, compression ratios, and spark plug condition. I strongly recommend taking your 1997 Buick Lesabre Custom to a reputable mechanic for a full diagnostic test—given that you've already spent significant money on parts without resolution. Once diagnosed, if you're confident in your skills, you can attempt repairs yourself to save on labor costs. Let us know what path you choose. Good luck with getting your car back to reliable operation.