can a cracked exhaust header through a prim. 02 sensor CEL?
getting code 41 which is the primary 02 sensor. The crack on the header is just berfore the 02 sensor dead in the middle of the manifold.

 

Yes it can, air leaking through the crack will disrupt the reading

 

so, what your saying is new manifold before new sensor. got it. thanks for the reply.

 

Or just have an exhaust shop weld the crack. Or if you do decide to replace the exhaust manifold you may want to consider buying an eBay header since buying new is pricey as hell and a junkyard may charge you a pretty penny also.

 

With eBay you have a chance of getting one with bad welds that could crack again., but for the average price of a generic header, it's almost worth the risk. I'd recommend getting the exhaust leak fixed soon, though. Running the car like it is right now, you have a chance of ruining the O2 sensor. If the O2S reads too much air, it tells the engine it's running lean. To compensate for the false lean reading, the ECU will start dumping more fuel, making the car run rich. Too rich, and the exhaust will foul the O2S, possibly the spark plugs, too. If it's running rich enough, you actually run a chance of fuel still burning in the exhaust, which does very unkind things to the O2S and catalytic converter.

 

Lol, out of the many eBay headers I've seen, not one was cracked. Turbo is a different story of course. But you're right, the risk is there...

 

Thanks for the info guys. I am going to have the crack welded either tomorrow or Monday. I have a spare vehicle so I will be able to drive it instead of the civ. Those OEM headers, they're cast right?

 

Right