VSC Light w/check engine light P1701 (03 4 Runner)

Folks this one has been stomped and I hope someone can provide some help. So I started getting a VSC/Trac light about a year ago and every so often the CEL would also come on. I've been running the scanner and I get the P1701 code (System too lean Bank 1). If I reset the code, the truck will run fine for about 60-70 miles and then will through the code again and all 3 lights will come back on, with the P1701 code again. I've ruled out zeroing/resetting the VSC and suspect that the p1701 is what is causing the VSC light to come on.

So, I replaced the MAF with a new OEM. I ran for about 60 miles and the lights came back on. I reset it again, ran another 60 miles and lights back on again. What other components should I be looking at?

Truck runs fine, Im getting about 18 mpg, no hesitation on acceleration, or miss fire. I can replace all the O2 sensors, but before I do - any suggestions or any way to test them?

Thank you

 

V6 or V8?

Check for a vacuum leak. There are a few vacuum lines under the hood that could have a tear or pin hole them. It's also possible the intake manifold is leaking, allowing additional, unmetered air to enter the engine. So it could be as simple as new vacuum lines and fresh intake manifold gaskets.

Make sure all the spark plugs are properly seated and maybe even replace them if they are getting close to needing changed anyhow.

Clean the throttle body, specifically the butterfly. With higher mileage, they tend to have build up on them that can cause weird issues. Likely not the problem but it doesn't hurt to do it anyhow. Brake cleaner on a rag, manually open it with your hand and wipe it out as best you can, both sides of the butterfly valve.

 

Could be a clogged injector?

 

Gents, thank you for the insight, I'll check these and follow up . Thank you

 

I had the exact same lights and cured it by replacing the front cat converter. Don't remember what the code was.

 

I'd consider running a gallon of lacquer thinner through the gas tank to clean the catalytic converter because it's cheap and easy.

I agree with post about about vacuum lines, but I'd do the lacquer thinner then spark plugs and then vacuum lines and I'd look for any oil going to the exhaust and causing trouble with your cats. Could be a faulty 02 sensor, but I like starting with the cheapest fix first.

 

BEAT ME TO IT!!! LOL . I Have two cans of it ready to go on a full gas tank!

 

For anyone reading this and going "WTF, lacquer thinner?", see this article - https://www.vehiclehistory.com/articles/cleaning-a-catalytic-converter-using-lacquer-thinner

 

Quick update. So I poured in 1 gallon of Lacquer thinner on a full tank, and ran the 4runner for about 250 miles with no codes. CEL usually came on at about 60 miles. Today, after 250 miles, the light came back on and this time it is the 0420 code. I cleared the code and have a replacement 02 sensor coming in. I may run a bit more Lacquer thinner with a higher concentration - seems it may have worked.

 

Nice!

You can also clean the O2 sensor, but at this point I'd be looking for another gallon of lacquer thinner and seeing if there's oil going to the cats. I don't know the layout of the engine but on the Lexus gs300 I had to replace the gasket where the oil was leaking.