silverbird

Hi,
I got a check engine light.
I pulled the codes.
They are.....
P0172 H-Fuel Trim System Rich Bank 1
P0175 H-Fuel Trim System Rich Bank 2

Car is a 16,000 mile 2002 Z06.
Installed Headers w/high flow cats, CAI and tuned back in 2007 at 6,000 miles.
Car runs GREAT.
I cleared the codes and put 50 miles on the car.
Codes have not re-appeared at this point.

Could these codes be caused by a loose gas cap?
A bad batch of gas?
Since it's both banks, my thought is that it's unlikely that both O2 sensors have gone bad at once?

Any thoughts or input?

Thanks,
Silverbird

K-Spaz

Your tune might have changed a little over time and now you're running rich. The DTC says you were running a >13% rich condition for 40 seconds straight.

I also get some wonky codes from time to time due to my headers. Seems the LT headers cool the exhaust so much that the heater circuits in my O2s don't like it if I'm just cruising along at light throttle and low rpms. That's more likely if it's humid outside and a little chilly. You might have been driving in conditions that were sorta unique, idk.

Given that those codes only set after the car is up to temp, and that it needs to see that condition for so long, I'd consider getting a new tune with a wideband. That's an eye-watering amount of rich condition. (outside the vehicle)

K-Spaz

Might also try re-torquing the headers. An exhaust leak will give a false fueling condition.

Here, try this.

RedRiderZR1

Well, when installing headers, a tune is a must. So much better airflow and less back pressure that will without a doubt change your tune. As far as running rich, that is because the car is running lean, so the PCM is adding fuel to (over)compensate. More than likely running really rich on decel as well. Get it in for a tune to fix these issues.

tblu92

LT headers are notorious for RICH codes--Reason being is that with LT's your front 02 bungs are moved further aft----sometimes as much as 3' !!!! This in turn causes your front 02's to not read correctly and not heat up correctly---Your front 02's commancand all your P/T fueling and will be carried over to WOT as well if positive making your WOT fuel pig rich and your engine lazy-----
There is NO 100% fix for this and is why LT's are illegal in most states----However the best fixes are
1. Install a set of REAR 02's onto the front locations--as the rear 02's are far more sensitive
2. LOWER both your 02 switching points-----Start by removing like 100 points to the entire table
Try to get an average front 02 voltages around .450 to .500 millivolts at P/T

silverbird

Thanks to all for the great information.

"That's more likely if it's humid outside and a little chilly."
That is exactly the conditions when the light lit up.

Since I cleared the code, I've put about 200 miles on the car...No Check Engine Light.
Car runs GREAT.

I'm having a tuner look at the current tune tomorrow.
I'll chime in as to where the car is/was at and if any adjustments were needed.

Thanks again for all the input!

Silverbird