What negative effects does not having the O2 sensor have on your car?

[TruRicanPlaya16]

I put some aftermarket headers on that were used from my cousin and the O2 sensor is a little messed up, so while im driving like after 5 minutes the check engine light comes on. Im not gonna be able to get a new one for another week or so, so I was wondering if anything bad can happen. Also I dont know a lot about cars so does this affect gas milage in anyway?

[GScivic7]

your car is going to throw a CEL and go into safe mode

[Civic_D16Y5]

what is safe mode?

[GScivic7]

retards your timing and shuts off or doesn't let engage a few features taht aren't necessary for your car to run ie. VTEC if so equipped. In a nutshell anyways.

[TruRicanPlaya16]

O i see, thanks a lot But would it affect gas milage in anyway, because I always heard having aftermarkets headers, you wouldnt even notice a difference. But it cut mine by at least 10-15 miles.

[Miataracer]

actually my o2 is bad right now also and i dont fall into limp mode... i think it just falls back on the factory preset numbers. i use a bit more gas.


this is good, this thread reminded me i need to order that damn thing tomorrow

[BullShifter]

Not having an O2 sensor will cause the engine to run very poorly and chance of burning up cat. I would recommend getting an O2 sensor before driving the car.

[GScivic7]

Originally Posted by Miataracer

actually my o2 is bad right now also and i dont fall into limp mode... i think it just falls back on the factory preset numbers. i use a bit more gas.


this is good, this thread reminded me i need to order that damn thing tomorrow

really...I've only come across like 3 cars with bad 02 sensors, and all three of them went into safe mode and threw a CEL because of it. The only reason i know they went into safe mode is because all 3 were VTEC and VTEC wouldn't engage in any of them.

Anyhow, yah you should replace taht sensor ASAP lol.

[TruRicanPlaya16]

Alright thanks guys, I ordered it today since they didnt have it in stock and ima be getting it Wed. Thanks for the advice.

[rbhale32]

Would simply replacing the O2 sensor bring back VTEC, or would you have to do anything else?

[superbluecivicsi]

The feds set an emissions guidline for manufacturers to follow. Manufacturers have deleoped the OBD2 system. the developement of the OBD2 system consist of sensors and actuators which all electronically controls the engine systems. an example of this is the primary o2 sensor on the obd2 system. when this sensor is bad, it sends a code to the ecu, which halts the operation of the o2 sensor because it is bad and not doing its job by reading the o2 measurements of the exhaust to determine how to effectively allow fuel to enter the fuel injectors to minimize the amount of pollutants exiting your exhaust by balancing the amount of fuel and air mixture. when this sensor goes bad, there is a trouble code, you'll see this as the CEL. This code automatically puts your ecu into open loop mode. in open loop mode, you will notice that your vehicle bogs a bit or alot depending on what mods you have that effect your fuel pressure. this mode is a default mode set by the manufacturers that runs rich (you notice this because your car feels laggier/bogs and the gas mileage sucks due to running rich).

[Toke138]

"what is safe mode?"

Thats where you press F8 while starting your car.