Thread: Exhaust ground

What does the ground on the exhaust from Cat to body actually do? Is it necessary for the 02 sensor to ground or something? I am putting a straight exhaust on with no cat so just wondering if I need to make a provision to mount a ground....I dont think there was on this car before,but I want to add one there if theres a valid reason for it.

For sensor ground for proper operation. All metal parts that have electric devices should be grounded to the vehicle body to prevent electrical back feeding which causes really strange issues with electrical components.

^^ So basically, more BS. Lol.

Depends on what O2 sensor you have.

I helped diagnose a car where the O2 sensor just wouldn't cooperate. Car had full stainless steel exhaust. Stock 3-wire O2 sensor didn't work well, so we upgraded to a 4-wire O2 sensor (to avoid the shitty ground quality a stainless steel brings to the mix)

Grounds are important

yeah this is why I asked because I remember reading a thread on gas mileage years ago by @Vadim regarding the 3 wire/4 wire and grounds.
I am putting a stainless jpipe/O2 housing and stainless catback exhaust back on my turbo car.Both The ECU and Wideband sensors are gonna be in stainless now so thats what prompted my question.
That ground wire by the shiter is all frayed and barely together full of oil,etc. I have a B13 so its not gonna have a rear o2 for the ecu but it will have a wideband sonsor there.
I woild assume the wideband one will be ok but maybe I should change to a 4 wire in the O2 housing.jpipe sensor?

Thanks again...the answers are all over the place on this one. I posted on facebook too...some answers are the same as here others arenot...lol

THANKS!!!
Keep the replies coming

I say keep it.

@DC Scotty Did a few ground tests to 3 wire O2 sensors, like adding ground wire to the thread of the O2 sensor, and found that they all didn't work out as well as simply using a 4 wire O2 sensor. Bosch 15727 is what I believe the correct sensor should be (but it's been a few years). It's listed as the universal option for newer Sentra's.

They are only $50 and well worth it if your on stock ECU's, if your rocking a NEMU you can just use your wideband for closed loop adjustments like us cool kids

You can never have too many (properly fixated and clean OEM) chassis grounds.

Multiple and/or improperly installed ground connections could create ground loops which cause noise in audio systems and screw with sensor voltages. Factory ground connections, if clean and solid are plenty in most cases. One exception that comes to mind is our beloved MAF sensor.

Totally fixed for ya. Thanks, Toddy!