idle skipping when warm CEL comes on

[dmo11]

i just bought a used 2005 mazda3 GT and the last couple days when my car is idling when warm it drops from around 800 to 300 then goes back up when it does this the CEL comes on and doesnt go off until the car sits and becomes cold again other then that it seems to drive fine anyone know what could be causing this?

[dmo11]

a little more info on the subject i pulled up the codes and got 0133 and 2159 one means vehicle spped sensor b range/performance and the other means 02 circuit slow response bank 1 sensor 1 .. anyone have any idea what i could do?

[sas]

The error P0133 means that the first oxygen sensor on the exhaust manifold
has long response time. This could be dirty or faulty oxygen sensor but also
it can be problems with fuel system. The computer is just determining that
there is long time between changes in fuel end exhaust system.
I don't see any info that Mazda3 has SPEED SENSOR "B" . The sensor "A" is main speed sensor on gearbox. In some cars sensor "B" is used for ABS or AWD.
Maybe this is bug and Mazda or WDS programmers have made a mistake whith tables.
P0500 Vehicle Speed Sensor "A" Malfunction
P0501 Vehicle Speed Sensor "A" Range/Performance
P0502 Vehicle Speed Sensor "A" Circuit Low Input
P0503 Vehicle Speed Sensor "A" Intermittent/Erratic/High
P0505 Idle Control System Malfunction
P0506 Idle Control System RPM lower Than Expected
.......
P2158 Vehicle Speed Sensor "B" Malfunction
P2159 Vehicle Speed Sensor "B" Range/Performance
P2160 Vehicle Speed Sensor "B" Circuit Low
P2161 Vehicle Speed Sensor "B" Intermittent/Erratic

More like you have really P0506.

I more inclined to the oxygen sensor version,because the effect is appearing
when the engine starting to run in "closed loop mode".

[dmo11]

thanks for the help im bringing it into the shop see if its a faulty sensor:bang i hope thats all it is

[dmo11]

hey one more question could a bad 02 sensor cause my idle to skip down like that?

[sas]

I think - yes. I see this picture so:
The cold engine running in open loop mode.
After engine is warm,is enabling closed loop mode.
Sensor has low sensitivity. Engine is starting to adjust trim from sensor,
making the mixture too lean and RPM is droping.
PCM see the droped RPM and switching back to open loop.
After sensor is heated by exhaust ,the sensitivity of sensor is raised and engine is working in normal mode.
If you don't notice the lack of power when accelerating this version is very convincing.
There is but. The second error end why sensor is dirty?
The error P0505 or P0506 is more related to air intake and IAC valve.
You can check and clean air filter maybe MAF too, check if engine coolant is near working temperatures.

sorry, have to go, the work

[dmo11]

well went down to the shop and there telling me its sue to a oxegen sensor cause of a cold start ?

[dmo11]

k i brang it in to the oly trustworthy shop in this place and he said it was cause one of my sensors had moisture in it and he cleaned asnd tightened it (wouldnt tell me what sensor) so i tok it and it drove fine for about 2 hours then it started up if i pushed in the clutch the revs would go from 500-1000 over and over and when i stopped the revs would go to about 750 then dip down to about 300 almsot causing it to stall then back up and keeps doing this .. does anyone have any suggestions on what it could be?

[sas]

Two-three weeks ago, here was thread with similar symptoms which was solved by flushing the injectors. You would to try. A prophylaxis is a good investment.
I don’t see possibility you can fix it yourself. There is too many factors you have to check and many of them must be checked by special tools. For mechanics this will be more quick and easy. You may check crack on intake system. Leaks in exhaust you should to hear. Carefully monitor the behavior of the car, this can help to mechanics.