Codes P0421,P0510,p1795
 

I have a 2000 millenia S and just retrieved codes P0421 whichpoints to the cat bank 1, P0510 (closed throttle position switch), and P1795 (closed throttle position switch). I have gotten the P0421 several times now, so how do I know whether to replace the cat? What would cause the P0510 & P1795 when the car appears to be running ok except for the TCS light is on? I found the discription for the code P0510 under the engine section of my repair manual and the P1795 under the transmisison section. Can anyone shed some light on this for me?

RE: Codes P0421,P0510,p1795
 

Hey Scott, Is that beast still giving you problems.:) If not one thing then another[:@]
The codes for closed throttle are just indicating that the both the PCM and TCM are not receiving a throttle closed signal from the TPS. With key on and engine off, at the TPS connector you should be seeing battery voltage at the Brown wire with accelerator pedal depressed and below 1.0 volts with accelerator pedal released. If always seeing battery voltage and no change then either the throttle could be too tight not allowing the throttle to close fully, TPS could be out of adjustment, or Closed Throttle Switch in the TPS is faulty.

RE: Codes P0421,P0510,p1795
 

Thanks! Since I erased the codes the P0510 and P1795 they have not reappeared, but the throttle pedal seems to feel like it issticking from time to time just coming off idle. I have'nt checked any voltage yet at the TPS. Could this be related to my TCS problems? The dreaded P0421 is now starting to get more fequent. Does this mean that I am going to have to put a cat on it? Babyhuey is the **** people!

RE: Codes P0421,P0510,p1795
 

yup. i just went thru this. i would erase the code, and it would come back. it got more and more frequent. finally, it was a weekly event. i changed out the oxygen sensors, and it still came back. so, i finally got a rear exh manifold, and changed it out. that was about 3 months ago, and no more code. car does run much better, too. not a bad job, but i had a lift and air tools. we got the manifold out and in without removing the jack shaft, which everyone says to do. actually, it just barely came out, but the new one went in really easy, like it was just a tad smaller. that cat is only 416 list price at mazda.

RE: Codes P0421,P0510,p1795
 

If throttle pedal feels like it is physically sticking at times would be more suspect of carbon accumulation inside the throttle body and not related to the TCS problem. Enough accumulation could also be holding the throttle open just enough to set the 510 and 1795 codes as well. There is only a small gap difference between switch being closed and open anyway. .005"-.010" difference is all it would take.

RE: Codes P0421,P0510,p1795
 

I just want tosay thanks to both of you Keninn and Babyhuey!I appreciate all the help! I have fixed the P0421 and if anyone needs more info on this go to PRECATS& O2 SENSORS!

RE: Codes P0421,P0510,p1795
 

I have not had the P0510 or P1795 lately, but the throttle pedal still feels like it is sticking! So I am going to start a new post! Go to THROTTLE STICKING for more info!