1998 328i emissions failure HELP!!!!!!!!!

[Sideswipe1]

1st BMW, Love it until now! VA emissions fail. started with 5 codes read from inspection station. Replaced Smog Pump, EGR Valve, all vacumm lines and now the shop said I need to replace the CAT. It only has 160k. The Cats not rattling so I noticed a weird flap valve on the exhaust tip. I am getting an
P0420 Catalyst System Efficiency Below Threshold (Bank 1). HELP!!!!!!!!!!!!!!!!!!!!!:eyecrazy:eyecrazy:eyecra zy

[bostonbmw]

I had the same Cat efficiency and it was the FRONT 02 sensors

[drummerboi]

yup try your 02 sensors first... CATs are saved for last...

[Eric93se]

Don't let those retards replace your cats. As others have said the code means the cats are not up to spec, BUT it only knows that because the o2 sensors are saying that, the o2 sensor are really what needs replacing. Replace the front two sensors, you have to drive for a while to let the codes clear on their own.

The front two sensors are the important ones because they help set the mixture, the rear two are only there to tell the computer if the cats are good or not, it does this by comparing the signal from the front to rear. But it works for a lot of us to replace the front two sensors to clear the cat code, and the added bonus is better fuel economy.

You should also check your intake boot (large rubber elbow) for cracks, its very common. Did you do spark plugs (check for oil in spark plug holes, indicates leaking valve cover gasket), air filter, check ignition coils for cracks and bad rubber insulator. If it feels sluggish off the line and the crank times are a little long it might need a camshaft sensor.

[TheFinanceGuy]

You should also check your intake boot (large rubber elbow) for cracks, its very common. Did you do spark plugs (check for oil in spark plug holes, indicates leaking valve cover gasket), air filter, check ignition coils for cracks and bad rubber insulator. If it feels sluggish off the line and the crank times are a little long it might need a camshaft sensor.

^ this. check that you have newish plugs, and a new air filter. Inspect the coil boots for any cracking/damage. replace as needed.
Check/clean you MAF. This can cause lean/rich mixture and cause O2 sensor error.

Why replace O2... test first, save money http://www.ehow.com/how_5193043_test-sensor.html

[Worstenemy453]

I love not having emissions.

[Sideswipe1]

Well I have priced the o2 sensor between 109 and 50 at Advance Auto. I will try that first. so now to find where they are located.

[Eric93se]

So those prices are high, but there are coupon codes to use at advance auto if you need to get them right away (search on slickdeals.com).

If you can wait a couple days, get them from rockauto.com they are $64 each right now, NTK brand which is OEM.

The sensors are in the header, you have to snake the wires up to the middle of the top engine cover. The tool to remove the sensors can be rented for free from advance auto parts store.

[hakentt]

if it comes out to be expensive converters, then there is a solution to reprogram your car computer so it won't trow a code for catalitic converters

[Sideswipe1]

Will I need a computer to do that

[Eric93se]

I wouldn't worry about that now just replace the two front o2 sensors and drive it so the codes reset on their own.

[bostonbmw]

amazon has a good price on NTK (oem) sensors

http://www.amazon.com/NGK-25013-Oxygen-Sensor-Packaging/dp/B001PNE8YA/ref=cm_cr_pr_product_top