P0134 keeps coming back
 

Hello Guys,

Can someone help me figure this out.

There has been a pending code on my Volvo S40 2.4i 2005 151000 Miles. It is P0134 now the interesting thing about this code is that when I clear it and then start my engine and Move i notice that my LIVE DATA reads the following which i deem as good.

FUEL SYS- CLOSED LOOP,
Short Fuel Trim and Long Fuel Trim Ok - STFT - 3 @IDLE and LTFT reads 0 @IDLE and reads when I accelerate.
MAF - btw 3-5 g/s
And other reading are Ok

But as I drive along I realized the the IAT reading is increasing to like 80-90C and the FUEL SYS shows OL-FAULT and i start to experience rough idle and then i realized the STFT & LTFT just stays at 0 and will not move even if i accelerate and then the P0134 comes back and lastly one thing i notice is that anytime this condition occurs, the EVAP_PCT% reading just stays at 0 but before the condition it gave readings.

Other symptoms are

Hard Acceleration
Exhaust smell

I had changed the Bank 1 O2 sensor before still it came back.


I need assistance.

Thanks

I'd be tempted to suspect the IAT sensor. No way, no how it should be reading that hot (even in one of the local Mesa, AZ summer days... though I swear it's close!). ;-)

I'd think that if the computer was really trying to correct for IAT that high, it would be doing some squirrely things to the fuel / air mixture (causing some of the other issues). On my 2005 V50 2.4i (identical engine) my IAT is always 10° F or so above ambient.

Sounds like a good bet. My wifes Subaru Impreza has 205K and it was kicking out bad AFR codes. Turned out the Mass Airflow Sensor was bad. The MAF in her car is integrated with the IAT. Live data on that was incorrectly too high and the MAF portion was reading badly as well.

Replaced it and its good to go.

How clogged is the air filter?? Not enough air could cause that as well.