I had this code p0420 for almost 3 years, but the light goes ON and OFF so somehow i passed the emissions, but now it's getting closer again and don't know what to do. I guess it's a air leak, but any ideas how to find and where to look for a air leak? The other code p0299 i have no idea, it's for my turbo, but the turbo works most of the time and sometimes when i push the gas pedal down the turbo don't works, so i am assuming maybe it's a air leak that is causing this two error.
Thank you !

I have isolated the front from the rear and determined the front is the cause to the pedal bleeding down. I bleed numerous times. Booster works perfectly, no air leaks. Only rear abs. I also replaced both calipers. To isolate the front, I disconnected the rear brake line from the master cylinder and plugged it. Pedal goes to the floor slowly. I disconnected both lines from master cylinder and plugged. The cylinder locks up, no movement.

Have had to rebuildthe A.O.D. automatic transmission, put in new clutch plates, band, and seals. Also put in new oil pump, and tork converter. I thought it was the valve body, so re-pulled thetransmission and went through the valve body. Still won't shift. This exact problem is what caused me to do the overhaul. Problem is still there. Anyone know the answer to this problem?

I had a P0300 code. Changed out fuel filter, throttle position sensor, cat converter, and coil for cylinder 2&3. The i got the P0420 code. If I just changed the cat with a brand new one, how can it be inefficient? Thanks for the Help.

Ive tried to find the right bolt and have no luck please help. Thank you

when you start the car the oil seal will fail on the filter. I have used several brands, does this on all brands. was told it was a pressure relief valve. replaced the pressuer relief valve in the oil filter area. It still blows the oil filter seal. need help.

If you turn on the key the fuel and temperature gauge needles will jump and return to the off position. need help to correct problem. Have already checked the solder connections.

some say yes n others ssay u dont have to. interested in this car but have not went n looked at it yet.

Clutch was replaced last year after it failed (the release fork was cracked). Pedal is just as stiff as it was with the old clutch. Also, the clutch release point on the pedal gets lower & lower as the vehicle warms up. No external fluid leak. Is it maybe an internal leak in the master? Thanks.

The light is off when you first start the vehicle and comes on when you drive. The dealership has reprogrammed it but I still have it come on. Does anyone know what I need to do?

Car was due for transmission flush. Check engine light was on, took to dealership. Diagnostic said we need new throttle body. They want over $700 to fix the car. Is this normal?

When speeding on highway the car puts out a smell like sulphur. Why would this happen?

Its an automatic transmission. this seems to happen when I drive at a speed from 35 to 40 to 50.
Whats causing this?

key will not turn. Need to know cause and repair costs

replaced timing chain cant get time set