PO442 Fault on GMC Safari Van - How to Fix and Pass Nevada Smog Check
During my recent Nevada Smog Check, I was flagged with a 'FAILED' result due to a PO442 diagnostic code. The smog inspector provided no specific explanation beyond stating the cost to address it was $100. I visited an autoparts store, which recommended replacing the fuel cap — I did so as the old one was visibly cracked. After installation, the check engine light turned off and the PO442 code cleared. However, upon rechecking, I received a 'REJECTED' result. The technician explained that after clearing the code (either via battery disconnect or software reset), the vehicle's internal monitors need time to complete a diagnostic cycle — typically requiring 1-2 days of normal driving. They suggested this is an internal timer in the Powertrain Control Module (PCM). My question: Does this mean there’s an internal timer that resets after a certain period? And if I replace the battery, does it still take time to reset? I’m concerned about repeatedly going back to the smog station for $12–$18 each time with no real fix. I’d like reliable information on what this 'drive cycle' actually is and where I can find official guidance. Any help would be greatly appreciated — I don’t want to keep paying fees just to pass a basic emissions check. P.S. The Nevada smog process feels more like a bureaucratic hurdle than a real environmental check.
Whenever a diagnostic code is cleared — whether by disconnecting the battery or resetting via software — the vehicle's monitors are reset. The Powertrain Control Module (PCM) requires a 'Drive Cycle' to complete its internal diagnostics. To resolve this, drive your GMC Safari Van for 1–2 days under normal conditions. If the check engine light does not reappear after that period, the system should be considered cleared and you should pass the smog inspection. Alternatively, you can search online for 'GM Drive Cycle PO442' or 'GMC Safari Van drive cycle procedure'. Follow these instructions carefully — they typically take only about 15 minutes. Perform this during off-peak hours (late night or early morning) to minimize traffic and ensure accuracy. After completing the drive cycle, return to the auto store or smog station and request a full monitor check. If all systems are clear, you should pass the emissions test without further issues.