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2004 Blazer P0171 and P0174 Codes: Hard Starting Issue After MAF Sensor Replacement

Model: 2004 Blazer Fault Code: P0171 Posted: 2012-01-25 13:23

I recently encountered P0171 and P0174 diagnostic trouble codes on my 2004 Blazer. I've already replaced the mass air flow (MAF) sensor, but the codes persist. While there are no drivability issues under normal operation, I'm experiencing significant difficulty starting the engine. The vehicle only starts reliably when I apply brake cleaner to the intake area—this suggests a possible fuel vapor or vacuum leak. Despite troubleshooting, I'm still unsure of the root cause. Does anyone have experience with this issue on 2004 Blazer models?

Related fault codes
P0171P0174
Comments (1)
Anonymous 2012-01-26 07:47

Yes, the hard starting is a key indicator—most likely your fuel pressure is too low or there's a vacuum leak in the intake system. Check the fuel pump and intake manifold gaskets for signs of wear or leaks.