Air fuel ratio sensor fault

**PAZ04U** · 17-09-2009, 08:35 AM

Hey guys,

I've been getting this flat spot at low revs especially when taking off, like tge car jerks and I get this puff of black smoke sometimes when i turn the car on.. It started happening less than a month after installing the CPe downpipe..
The engine light came on the other day so I contacted my friend at Mazda and he told me to pop in this morning to check what the fault is.. He reckons it's a air fuel ratio sensor that's faulty and it's found in the catylatic converter..
Now from what i remember when installing the downpipe, there were 2 O2 sensor and no sensor in the cat, what's the deal here?

Someone help me out here...

**kmh001** · 17-09-2009, 09:53 AM

Is it a cat-less DP? They commonly cause CEL's because the two oxy sensors report the same data to the PCM which is programmed to interpret that as a cat failure.

**PAZ04U** · 17-09-2009, 02:42 PM

No its not a catless downpipe.. It's the catted one I think version 2.. The version they reckon didn't bring up any CELs...

**kmh001** · 17-09-2009, 03:20 PM

Ok, I think the next thing to do is to find what code is causing the CEL. Can your mate at Mazda tell you the code? Or do you know someone with a Dashhawk or similar?

**PAZ04U** · 17-09-2009, 04:09 PM

I asked my mate and he said his busy so I don't think he can get it and no I don't know anyone with a dashhawk.. He just says the code brings up a air/fuel ratio sensor fault.. The car is running too rich..

**MattMPS3** · 17-09-2009, 04:19 PM

Given that its affecting the cars AFR's i.e running rich, I would assume the primary (first) sensor is to blame (the second sensor only really ensures the cat is functioning within spec), can you check that it hasnt somehow come loose, maybe also check that the connections are also secure. Is there a chance you may have damaged the sensor during the install ?

**PAZ04U** · 17-09-2009, 04:47 PM

I don't think we damaged them my mechanic installed it I just gave him a hand.. I don't think he would of damaged it..

**MattMPS3** · 17-09-2009, 04:56 PM

A thought has just come to mind, which bung was the sensor installed into, as the cp-e downpipe has 2 locations available for the primary sensor, maybe the wrong hole was used.

**PAZ04U** · 17-09-2009, 05:28 PM

Well i bought the pipe off Karl (kblume) and I just used the hole with no bung in it.. Cause the other hole had a bung in it..

**2XS** · 17-09-2009, 09:57 PM

Try checking the MAF housing and maybe clean the sensor.

I have heard this problem with std Mazda 3s and the problem was a dirty MAF sensor.

Let us know how this goes. I know the CEL says AFR and o2 sensor, so, it sounds very similar.

View Profile · 17-09-2009, 10:05 PM

Originally Posted by PAZ04U

Well i bought the pipe off Karl (kblume) and I just used the hole with no bung in it.. Cause the other hole had a bung in it..

Where are you located mate, I have a DH...

**PAZ04U** · 17-09-2009, 10:38 PM

In burwood.. The cel is gone now though, they cleared it after they checked the code this morning..

2XS when cleaning the maf sensor do I just spray Electra clean on the little black ball that hangs down or what?

View Profile · 17-09-2009, 10:40 PM

Previously ive used electrical contact cleaner and just smothered it, then dryed it off with a can of compressed air.

**PAZ04U** · 18-09-2009, 04:29 PM

P2188 is the fault code number..

**lazydog** · 18-09-2009, 04:30 PM

The o2 sensors are very very sensitive. Be careful you didn't bend the wiring when trying to put the sensors back in.

Is it missing?

**PAZ04U** · 18-09-2009, 10:20 PM

Yes it is missing a bit.. At low revs especially when taking off..

**PAZ04U** · 24-09-2009, 09:46 AM

Took it to Mazda this morning and they said they are replacing the O2 sensor closest to the manifold...

View Profile · 28-09-2009, 09:02 PM

Revival!

here are some logs we took tonight, if someone could have a quick look it would be most appreciated

I zipped them as there are three files associated with each log (and two logs)
Logs.zip.zip

I was not too sure what to log so the first run we logged;
Spark adv
RPM
Boost
A/F from sensor
Fuel Pressure

the 2nd run we logged;
RPM
Boost/vac
Abs throttle pos
spark adv
wastgate solenoid DC%

View Profile · 29-09-2009, 08:59 AM

Any takers?

If you would prefer I email the logs please let me know and I can send them to you unzipped.

Cheers
Justin

**tricache** · 29-09-2009, 09:08 AM

Did mazda end up replacing that sensor? The CEL code is "SYSTEM RUNNING RICH ON IDLE" so its definetly a fuel problem.

I would be checking intake and also those sensors, cause the car is pretty much flooding itself with fuel.

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