Smog Testing a Plug-in Prius Can Increase Emissions

For this guy anyway.

My 2012 PiP was coming up on it's 6th year of registration, when I was notified by the DMV that I had to have the vehicle Smog/Emission tested. Really, it's just a silly exercise of a quick visual inspection and a scan of the OBDII for a few metrics. No dyno or measuring exhaust at the station.

Aside from the opportunity for the State to collect some revenue, not too much of a hassle, right?

Well, leave it to some bad timing - just days before I had a fuse replaced on the main battery as part of our recent recall. None of my settings were lost, so I figured they used a battery saver. Regardless, when I took my PiP in for emission testing, they tell me it's not ready to test and "have you unplugged the battery recently?"

I figured the recall fuse change must have still reset the OBDII monitors, despite no display settings lost. So they tell me, no problem, just drive a hundred miles and bring it back in and it should be ready to test. I even had the ICE run for two complete warm up cycles just in case the emissions test needed to capture ICE data, which I figured would be the case since there are no vehicle emissions during battery use. For good measure, I put 150 miles on the vehicle. Back to the station, but still no pass.

It might take a few hundred miles, actually, they now told me. I don't drive the PiP that much, commute is 3.5 miles each way, and I mostly use the ICE for long trips or when the vehicle has to cycle the ICE every 100+ miles. They told me there were some systems still not ready, but would not elaborate much.

Perhaps others here know this, but after some reading, apparently the ICE has to be running for some time to get the Oxygen Sensor/Heater and Catalyst up to temperature to ready the system. So I plugged in my OBDII scanner and downloaded an app on my iPhone that has emissions metrics. Indeed, it showed that the O2 Sensor and Catalyst were not ready. After running the ICE for about 10 minutes on the freeway, these metrics went to "pass" level. I took the car in and indeed it passed.

Now I suspect most PiP owners will not have the misfortune to have the ODBII monitor reset so proximate to to their emission testing. But for the unaware who may have recently changed a battery, gone for recall work as I did, or in some other way had the OBDII monitor reset, and do little freeway driving and run mostly in EV mode, you'll be contributing to more emissions for a while just to prove your PiP can pass and emission test that few doubted.