Trying to find the issue with 2006 1.3L Yaris hatch:
Check engine light comes on after driving for a while, usually after highway use.
Other than the check engine light coming on the car is running very well, good fuel consumption, smooth idle and acceleration.
Get a PO420 but if I do not clear it, will through a P0171 code as well.
Mechanic said PO420 is the most difficult code to troubleshoot due to being generic.
Connected to his expensive professional diagnostic equipment, could not find the issue.
Encouraged me to keep trying things, suggested to clean the throttle body, which I have done.
Car now runs better with faster acceleration.
My scan tool does not produce live data but will post Freeze Frame of when the issue happens, 2x examples
DTCFRZF PO420 PO420
FUELSYS1 CL CL
FUELSYS2 N/A N/A
LOAD_PCI(%) 56.5 63.1
ETC(C) 83 83
SHRTFT1(%) -1.6 -6.3
LONGFT1(%) -3.9 -3.1
RPM(/min) 2131 1914
VSS (km/h) 42 51
SPARKADV( ) 31 28
IAT(C) 41 43
MAF(g/s) 7.79 10.17
TP(%) 20.0 22.0
O2B1S1(V) 0.740 0.625
SHRTFTB1S1(%) -1.6 -6.3
O2B1S2(V) 0.740 0.700
RUNTM(sec) 693 606
EVAP_PCI(%) 23.5 51.4
WARM_UPS 5 6
CLR_DIST(km) 122 59
BARO(kPa) 103 103
CATEMP11(C) 560.70 589.50
CATEMP12(C) 560.70 589.50
VPWR(V) 13.632 13.632
LOAD_ABS(%) 32.0 46.7
EQ_RAT 1.000 1.000
TP_R(%) 4.3 6.3
TP_B(%) 52.5 55.3
APP_D(%) 20.4 22.4
APP_E(%) 35.7 37.6
TAC_PCT(%) 19.6 21.6
CLR_TIME 3:h:06m 1h:49m
Will purchase a better scan tool that does provide live data if required. Hoping someone can see an irregularity or a maxed-out threshold in this data and tell me what to look for?
Do not think it is smart to keep replacing parts without knowing it is likely to fix the problem.
Thanks in advance for any comments or suggestions.