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2000 Dodge Neon Won't Start After P0340 and P1684 Error Codes - Solutions & Diagnostics

Model: 2000 Dodge Neon Fault Code: P0340 Posted: 2010-09-29 09:09

My 2000 Dodge Neon (2.0L 4-cylinder, automatic transmission, 145,000 miles) suddenly stopped starting. The engine turns over but does not fire. Previously, it displayed error codes P0320, P0340, P1391, and P1684. After confirming that the fuel pump, starter, and spark plugs are functioning properly, I replaced the ignition wires, spark plugs, camshaft position sensor, and battery. The issue persists—engine turns over but fails to start. After replacing the camshaft position sensor, codes P0320 and P1391 cleared, leaving only P0340 and P1684. While I'm not overly concerned about P168-than, the persistent P0340 code is raising concerns. Multiple online forums suggest that a faulty crankshaft position sensor or a damaged timing belt could be responsible. I previously noticed oil on plugs in cylinders 2 and 3, which may indicate an ongoing issue—but I don't believe this explains the sudden failure. Given the vehicle's age and mileage, I'm wondering if a timing belt failure is likely. Could the camshaft sensor be sending incorrect signals due to misalignment or a broken timing belt? Any expert advice on diagnosing this issue? What steps should I take before attempting a timing belt inspection or replacement?

Related fault codes
P0340
Comments (3)
Anonymous 2010-10-03 11:24

This post has received several views but no clear solutions—any experienced users with similar issues? Update: I've now replaced the crankshaft position sensor, but the car still won't start. The P0340 code remains. As a beginner when it comes to timing belts, I'm hesitant to spend an entire day working on this. Are there any other diagnostics or checks I should try before investing significant time off work? Any suggestions would be greatly appreciated!

Anonymous 2011-10-03 00:52

First, check if the engine is turning over with proper timing belt movement. If the timing belt has broken or lost teeth, the camshaft sensor won't send a signal to the ECU, which can prevent spark and fuel delivery—potentially leading to valve damage. Always follow the manufacturer's recommended timing belt replacement intervals. In hot climates (above 100°F) or cold environments (below freezing), consider using severe service maintenance guidelines. Let me know how this resolves your issue.

Anonymous 2011-10-03 05:02

If you disconnect the camshaft position sensor and the engine still doesn't start, it may indicate that the timing belt is out of alignment—this would cause a loss of proper valve timing. Some aftermarket sensors are known to be unreliable; ensure you're using OEM or high-quality replacements when possible.