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2000 Chevrolet Impala P0300 and P0446: What Do These Codes Mean? Fix Without Breaking the Bank

Model: 2000 impala Fault Code: P0300 Posted: 2016-01-06 16:11

Hello, I purchased my 2000 Chevrolet Impala about eight months ago and it has run fine until recently. After running out of gas, I took it to AutoZone for a diagnostic check. The scan revealed two trouble codes: P0300 (Random Misfire Detected) and P0446 (EVAP Canister Purge Vent Blocked — appearing twice). What do these codes mean? I was advised to replace the spark plugs and ignition wires. Is this the correct solution? Are there other steps I should take before spending money on repairs? I don’t have much experience with car maintenance, and this vehicle is essential for my daily commute. Every mechanic I’ve contacted charges $100 just to inspect it — which makes me hesitant. Thank you in advance for your help! P.S. The fuel gauge was not working, and someone previously reset the odometer — this may have contributed to running out of gas unexpectedly.

Related fault codes
P0300P0446
Comments (7)
Anonymous 2016-01-06 16:28

Please describe how the vehicle is currently performing: - Is the Check Engine Light (CEL) on? - Does the engine miss or run unevenly? - Are there any issues when refueling — for example, does the pump keep shutting off? A common theory is that running out of fuel caused the P0300 misfire. Consider addressing the refueling issue. If you decide to replace spark plugs, use AC Delco products (known for reliability). Note: It's generally recommended never to let your fuel level drop below 1/4 tank.

Anonymous 2016-01-07 10:49

Thank you for the helpful response. The car is currently running smoothly — no missing or unusual noises. I haven’t experienced any problems when refueling. The Check Engine Light is on, but there are no noticeable symptoms during operation. I was planning to replace the spark plugs and ignition wires as suggested. The fuel gauge malfunctioned, and someone previously reset the odometer — this explains why I ran out of gas unexpectedly. Thanks again for your time!

Anonymous 2016-01-07 11:09

If there is no annual emissions testing in your area, running out of fuel was likely the root cause of the P0300. In this case, the P0446 code can be temporarily deprioritized — but fixing the fuel gauge is essential to ensure proper EVAP system monitoring.

Anonymous 2016-01-07 15:04

I appreciate your insight — I'm wondering what the best approach is for resolving the P0300. A mechanic suggested replacing spark plugs, ignition wires, and possibly the fuel system components, which would cost around $340. Is this overkill or a necessary fix?

Anonymous 2016-01-07 15:33

You mentioned the vehicle runs smoothly with no missing — is that accurate? Note: Modern vehicles do not require traditional 'tune-ups' as ignition timing, dwell angle, idle control, and other settings are managed by the engine computer. Replacing spark plugs may be needed, along with inspecting wires, air filter, and cleaning the throttle body. However, if your car runs well and you're on a tight budget, consider that running out of fuel likely triggered the P0300. Try clearing the codes and test driving the vehicle over the weekend to see if they return. The P0446 code is tied to refueling issues — fixing the faulty fuel gauge will resolve both the EVAP system monitoring and underlying root cause.

Anonymous 2016-01-07 16:30

Yes, that's correct. The mechanic I consulted said I need spark plugs, ignition wires, and a full fuel system inspection — all totaling around $300. It seems like a comprehensive but expensive fix.

Anonymous 2016-01-07 16:59

AutoZone or similar stores can clear the trouble codes using their diagnostic tool — sometimes you need to manually press a 'clear' button due to policy restrictions. Alternatively, disconnecting the negative battery terminal for several minutes will reset the engine control module and clear the codes. This method is free but will erase all radio presets.