System too rich Bank 1 and Bank 2

airitech · September 17, 2016

Hey guys, i have a bluetooth obd2 connector, and i use it with DashCommand, its an iOS app and its pretty sweet it shows you everything in real time. The reason i bought it originally was as a scan tool, i have a check engine light and its System too rich bank one and bank two, ive looked online to find out what could be wrong and it says that it could be a bunch of stuff. But what really caught my eye was that it could be caused by a bad oxygen sensor.. Dash Command allows you to see What the O2 sensor is showing in real time and it looks funky. Please note that the video was taken at idle, while the truck was up to running temperature.

https://sendvid.com/jrrol452

as you can see from the video, it goes up and down and up and down constantly while at idle, that seems weird to me.

I have a Spectre CAI, but the code was there before i got it. And i also rechecked all the seals the the intake is sealed up perfectly no leaks.

Also,

DashCommand has a feature under diagnostics that shows all of the systems available, when the code appears the Oxygen sensor and Oxygen sensor heat becomes unavailable.

Let me know if you think that the O2 sensors are bad, and let me know where i can pick one up for a good price!

Ive attached a photo of where it shows the O2 sensor not being able to be read. But when it says it cant be read it still shows me the O2 sensor live reading which is always, even when im driving, going up and down and up and down.

https://gyazo.com/cd8e729c732f216e5a41e8159b31c2bf

Thanks!

wehowardjr · September 17, 2016

The up and down at idle is completely normal. What codes, if any, is the truck showing? That would help a lot.

This video is for an Envoy running lean but shows the O2 sensors in action.

airitech · September 17, 2016

it constantly shows the p0172 and p01725

wehowardjr · September 18, 2016

Here is an article I found concerning those 2 codes. Hope it helps lead to a fix.

http://repairpal.com/OBD-II-Code-P0172-and-P0175

devildog12105 · October 18, 2019

hey everyone, i have a 2013 gmc sierra 2500hd throwing the same codes, so far the dealship told me the truck needed a MAS, all new plugs and wires, both up stream o2 sensors, and a new Y pipe with all 3 cats. truck is still running rich and i have a spark knock at low RPMs. im sick of throwing parts at it. can anyone help?

sefiroxx · October 19, 2019

Clean the maf. Use a scanner and check that the front O2 sensors are cycling, if not, then replace them.

Pull the injectors and send them for cleaning

swathdiver · October 19, 2019

On 10/18/2019 at 7:13 AM, devildog12105 said:

hey everyone, i have a 2013 gmc sierra 2500hd throwing the same codes, so far the dealship told me the truck needed a MAS, all new plugs and wires, both up stream o2 sensors, and a new Y pipe with all 3 cats. truck is still running rich and i have a spark knock at low RPMs. im sick of throwing parts at it. can anyone help?

Inspect your plugs and wires, if over 100K miles on them, put new ones in. Get the little 2 bottle kit, throttle body and Mass Airflow Sensor cleaner from Walmart and take care of those two. You should not be replacing the cats unless they are throwing codes P0430 and P0420. I suspect that if she's really pulling fuel, that there is a large vacuum leak and the intake gaskets are the usual culprit.

If you have a scan tool, you can set up a graph for the upstream O2 sensors and spray water or propane around the intake gaskets along each cylinder head and watch the O2 sensors.

Were there only two codes or more?

devildog12105 · October 20, 2019

P0172 and P0175 are the only codes thrown, MAS and plugs and wires all new, had one up stream O2 bad so replaced both, the right side cat was plugged which I think cooked the o2, the temp going into the cat was 100 degrees hotter the coming out, the left side was only 10 degrees difference, told me the cat was plugged, down steam sensors seem to be alright but I think are trying to compensate for running rich, also checked the ECT, reading correctly. I was thinking bad fuel pressure regulator or big vacuum leak??

swathdiver · October 21, 2019

4 hours ago, devildog12105 said:

P0172 and P0175 are the only codes thrown, MAS and plugs and wires all new, had one up stream O2 bad so replaced both, the right side cat was plugged which I think cooked the o2, the temp going into the cat was 100 degrees hotter the coming out, the left side was only 10 degrees difference, told me the cat was plugged, down steam sensors seem to be alright but I think are trying to compensate for running rich, also checked the ECT, reading correctly. I was thinking bad fuel pressure regulator or big vacuum leak??

The downstream sensors measure the health of the cats and when graphed, are fairly constant. The upstream sensors fluctuate, moving up and down a lot once warmed up.

Yes, I suspect a large vacuum leak, probably your intake gaskets. What are your Long Term Fuel Trims at idle or driving around? If they are lower (higher number) than -10 you likely have a leak somewhere.

devildog12105 · October 21, 2019

Long term trim was -28 and -29

swathdiver · October 22, 2019

6 hours ago, devildog12105 said:

Long term trim was -28 and -29

Wow, you've got a massive vacuum leak. The usual suspect are the intake gaskets. Check all hoses going to and around the intake and throttle body first and then run the test to check the intake gaskets.

tbarn · October 22, 2019

P0172 and P0175 are "rich" codes. The negative (-) numbers mean that the ECM is taking fuel away from a neutral condition. Hence a rich condition.

sefiroxx · October 22, 2019

Yes, too much fuel so ecu is cutting back

- leaky fuel injector(s). Since both sides have negative ft, 2 or more injectors going at the same time is less likely
- fuel pressure regulator failing allowing too high pressure (and too much fuel)
- MAF failing suggesting more air than actual. ECU adds fuel to match air, and then cuts back once it sees the the o2 results

Note, Vacuum leaks result in too much air so ecu adds fuel to compensate (positive ft) and sets a lean condition code.

devildog12105 · October 23, 2019

The dealer said today that they do not like how the MAS is acting when the truck fires up when cold, it’s brand new, they sold it to me 2 weeks ago but they are putting another one in. also GM has a bulletin out for an issue with the throttle body and causing a possible rich problem, comes with a new mounting gasket and a few parts to be changed out, we will see if it helps.