Permanent Code

I was doing some maintenance/cleaning, unplugged the mass air flow sensor and forgot to plug it back in before starting the engine. Obviously threw a check engine light, corrected the issue and cleared the light with a scanner. There’s still a permanent code lingering around, anyone have any experience with it? My first thought is I’ll have to run the engine enough to satisfy the ECU that the issue is repaired but I’ve already driven the vehicle about 50mi and every time I scan the ECU I still keep getting the permanent code. The code is for the air flow sensor.

 

Ive seen codes, sitting from date of reaching port on new runners. Some, although cleared, stay in limbo for future help of a diagnosis. If your check engine light is off. And remaining off, for me, i wouldn't worry whats filed away.

 

I'm wondering if disconnecting your battery for a bit and resetting everything would get rid of the code.

 

When i was playing around with a trd intake i bought, then decieded against it, i did get some dash lights. I pulled the positive cable off the battery, re-installed the oem air box, put the pos cable back on, and every light went off. That said, in the obdII memory, there's probably still some stuff you can see even though dash warning lights are all off, and all fine. I know, there are some things, even when cleared, remain. Like air bag deploy and other. Cleared, yep, but hangs in memory.

 

The only issue that worries is that I have to renew my registration, and have to take it to the smog station. So my worry is that even though I know my rig is running fine without issues and a CEL, that their scanner will pick up on the code and fail me.

Normally yes, but the permanent codes are a “deep cycle” sort of thing that require driving and/or fixing the issue to satisfy the ECU.

 

Youll be fine boss.

 

Yes. In many states a lingering code will make your vehicle fail the emissions test. It’s no effort to try disconnecting the battery, but my bet is that you will have to put on miles to clear the code. Perhaps not just any miles. I had a Land Rover with lingering codes and to clear them I had to drive 100 km, a peculiar mix of freeway, stop and go, and descent.

 

Did that cure the issue? That’s what it seems I’ll have to do from everyone’s recommendation.

 

Over the years I've seen many threads about how to determine when a car is ready for emissions testing - maybe a new tune has been loaded, battery disconnected, etc. It's easy with the Torque app which I've been using for years. Here's how to do it:

First, on the opening screen, hit "Realtime Information" to go to the screen where you've setup all your gauges:


On your gauges screen - below - touch and hold an empty part of the screen to bring up the popup at the bottom and choose "Add display":


Under "Display type" add both "Emissions monitors since DTC clear" and "Current drive cycle status":


And this is what you'll get on your gauge screen. It does change in real time, so as you're doing your drive cycle you can see the monitors change to "completed" and you'll know you're ready to get your inspection:

 

Seems pretty informative, how do I connect to the car?

 

From youtube on corolla ,probably the same on 4Runners......
I have Techstream and i think they can be cleared from there too.

 

Do a search for the torque app and how to use it. It requires a little $10 bluetooth adapter from Amazon. Look for an ELM327

 

I have a Carista one, I’ll give it a try and see if I can pair it with that one. Thanks for info!

Might need to invest in a techstream, thanks!

 

The Carista one does work with Torque. I have that one too.