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2006 Chevrolet Trailblazer P0300 P0128 P044-9 P0601 Fault Codes: Causes and Solutions

Model: 2006 Chevy Trailblazer Fault Code: P0128 Posted: 2018-10-27 11:10

I recently replaced the alternator on my 2006 Chevrolet Trailblazer with a 4.3L V6 engine, but now I'm seeing multiple diagnostic trouble codes: P0300, P0128, P0449, and P0601. I also replaced the battery, which was at 12.68V when measured before starting. After the engine started with accessories (heater, headlights, radio) on, the voltage reading increased to 14.79V while running — this seems within normal range. I'm wondering if there's a common underlying cause for all these codes appearing together. The vehicle occasionally dies suddenly, loses power, and won't start, then restarts after about two minutes. As driving duration increases, the intervals between these episodes get shorter. Has anyone experienced similar issues? I've tried resetting the Powertrain Control Module (PCM) by removing fuses #10 and #28 for one hour — will this help resolve any of the codes? Any insights into how to troubleshoot each code individually or identify a root cause would be greatly appreciated. Thanks in advance, Doug.

Related fault codes
P0128P0300P0449P0601
Comments (7)
Anonymous 2018-10-27 11:55

Have you reset the engine control module (ECM) after replacing components? If so, do any of the codes reappear after restart?

Anonymous 2018-10-27 14:31

These symptoms — sudden power loss, inability to start, and intermittent recovery within two minutes — suggest a potential electrical or sensor issue. The problem seems to worsen with increased driving time.

Anonymous 2018-10-27 15:42

The sensors associated with these codes (like the coolant temperature sensor, oxygen sensor, and EGR valve) all require stable power and signal input from a properly functioning PCM. Please verify that battery voltage remains above 13.5V while the engine is running with accessories on, and ensure there's no significant voltage drop due to AC or load components.

Anonymous 2018-10-28 11:56

Battery reads 12.68V when off, and reaches 14.79V during operation with heater, headlights, and radio on — this indicates a healthy charging system. I’ve already attempted a PCM reset by removing fuses #10 and #28 for one hour. Will now monitor if any codes return after restart.

Anonymous 2018-10-28 13:41

It may be more effective to address each code individually, as they likely stem from different underlying issues. Referencing the official trouble code database on this forum can provide specific solutions for each P-code.

Anonymous 2018-12-10 06:49

On my 2006 Trailblazer, I discovered that a fuse in the driver’s side fender under the hood was loose — it took weeks to locate. After securing the connection, all electrical issues resolved immediately. Try checking your fuse panel for similar problems; this could be a simple fix.

Anonymous 2020-08-23 11:50

What was the final solution for your issue? I'm experiencing very similar symptoms with my Chevrolet truck — sudden shutdowns and difficulty starting after short drives. Any advice on diagnosing or fixing these codes would be helpful.