P0172 fault code after Check VSC

[Brechin Slate]

Hi all

Had the lovely Check VSC warning come up a few times recently but cleared it by disconnecting the Battery to see if it was just spurious. It wasn't and returned after 2 days each time. I bought the Techstream kit from eBay (TaggyTech, excellent) and ran a test this morning. Only one fault code, P0172, system too rich Bank 1.  I can make adjustments to all kinds of things using Techstream but what should I be looking at first? On my old cars I'd have been using a Colourtune and screwdriver!  Please see attached pic from laptop.

Regards to all.

[Shahpor]

Hey Mike,

If only it was that simple still

Have you checked things like vacuum leaks and temp sensors?  It can be rather involving to diagnose, so have a look at the attached HTML file to give you some ideas.

*edit* that didn't work. I will message you instead.

[normski2]

As it’s very easy to do .... I’d remove and do a solvent clean of the maf sensor. Then you can dismiss that if the light is still on.

Have the upstream fuel/air sensors ever been changed?

[Texas]

Here is a basic explanation of the P0172 error code for Lexus with some areas to investigate but the symptom of excessive fuel consumption doesn't really apply to a 250 I guess!!!!!

https://www.autocodes.com/p0172_lexus.html

paul m.

[Texas]

Seeing you have TechStream to hand check this recent thread on error P0171 (too lean) I know this is not your fault but it has the details for the voltage specs for the O2 sensors

https://www.lexusownersclub.co.uk/forum/topic/112998-system-too-lean-error-codes/

in particular this post

https://www.lexusownersclub.co.uk/forum/topic/112998-system-too-lean-error-codes/?do=findComment&comment=1029658

paul m.

[Brechin Slate]

Hi all

Followed forum advice and did the easy stuff, checked hoses, cleaned MAF sensor even though it was spotless.  All back together and then a 60 mile run under various road conditions. So far all good, I'll let you know if anything changes.

Regards to all 

Mike 

[normski2]

Good news Mike.

Here's hoping that's done it.

I do my MAF clean every 8000 miles or so. Its never looked dirty but its kinda tricky to see right down the tube where the wire goes. So I just do it anyway.

The good news is that if it is the Bank 1 Sensor 1 that's playing up .... its the easiest one to replace. 15 mins tops.

[Texas]

Fingers crossed it was that simple a fix for you.

paul m.

[Brechin Slate]

Every cloud has a silver lining.  The car now seems to be running better than ever and my fuel consumption figures are better.  Now getting 34 mpg on a short (7 mile in each direction) daily commute.  I was getting 29 mpg on the commute before and thought that was reasonable. Happy.

Thank you Shahpor, Normski and Texas.

Regards

Mike

[normski2]

That’s good news. Hampshire is a big county.. so this may be a pointless offer. My closest point to Hants would be Ringwood. I work near Verwood. If you need to do the oxygen sensors at any point I have the requisite socket for the sensor. You are welcome to borrow it at any time. Bank 1 sensor 1 is dead easy. Bank 2 sensor 1 is a little more tricky, but doable.

I’ve done both on my car so can offer assistance. Newbies guides are excellent and easy to follow.

[Brechin Slate]

Excellent, Normski, thanks, if the fault re occurs that will be my next step. I'm in Barton on Sea but pass through Ringwood on my way to Poole every Tuesday.

[Shahpor]

Glad to hear the car is doing well

[kaboebi]

Hello, I have a P0172 and a P0175, bank 1 and 2 rich..... what can that be? i changed the MAF sensor but I was told these cars, Lexus IS 250, 2010, 25k miles, don't like after market sensors. Is that so? the error codes came back. what can be affecting both banks? I don't think both oxy sensors can go bad at the same time.

[Texas]

Any components with wires attached should be replaced with OEM only or you could get into a world of pain