Question about Cars & Trucks
Catalyst system below threshold bank 2
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Posted on Jan 02, 2017
SOURCE: Three trouble codes
Trouble Code: P0421
Catalyst Efficiency Below Normal (Bank 1)
Air leaks at the exhaust manifold or in the exhaust pipes
Catalytic converter is contaminated, damaged or has failed
Front HO2S and/or the rear HO2S is loose in the mounting hole
Front HO2S older (aged) than the rear HO2S (HO2S is lazy)
Front HO2S or rear HO2S is contaminated with fuel or moisture
Trouble Code: P1173
HO2S-21 (Bank 2 Sensor 1) Circuit Malfunction
Base engine mechanical fault affecting one or more cylinders
EVAP Purge valve stuck or the hoses to the valve are reversed
Fuel metering fault (fuel injector sticking open or leaking)
Fuel pressure too low or too high, fuel supply contaminated
HO2S element is contaminated or the HO2S heater has failed
PCV system has air leaks at the valve or related hoses
Trouble Code: P0174
Adaptive Fuel Trim Too Lean (Bank 2)
Vehicle driven low on fuel or until it ran out of fuel
One or more injectors restricted or pressure regulator has failed
Fuel delivery system supplying too much or too little fuel during cruise or idle periods (e.g., faulty fuel pump, or dirty fuel filter)
Air leaks after the MAF sensor, or air leaks in the PCV system
Air leaks at the EGR gasket, or at the EGR valve diaphragm
Exhaust leaks before or near where the front HO2S is mounted
HO2S is contaminated, deteriorated or it has failed
Fuel control sensor is out of calibration (i.e., ECT, IAT or MAP)
Base engine -mechanical- fault affecting one or more cylinders
Posted on May 18, 2009
That's a pretty RELIABLE code!... You have a bad CAT (Catalytic Converter). Trust it to be accurate. The conditions which set this code is when the Upstream O2 sensor's data/signal is compared to the Downstream sensor's data/signal... when they are nearly identical, that's when this code is set (unless you have an exhaust leak).. If there is an exhaust leak.. repair it, then retest/recheck.
Posted on May 31, 2009
7 out of 10 times that means that one of the cat's have gone bad. Most of the time it happens when your mileage is around 100,000 miles. The only thing is to do is to change the bad cat.
Posted on Aug 30, 2009
before doing anything make sure you have to code for your radio if you have the antilock radio feature!
disconnect the battery wait a few moments I can only give this info for a quick fix this will reset the computer and if it was just a glitch it should be fine after this should it reacour it is a oxygen sensor
Posted on Mar 04, 2010
SOURCE: code of PO174 1 system
hi,my friend, you can try, Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required. Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady). Inspect the downstream heated oxygen sensor (HO2), replace if necessary Replace the catalytic converter
hi,my friend, you can try,
Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
Inspect the downstream heated oxygen sensor (HO2), replace if necessary
Replace the catalytic converter
Posted on Sep 15, 2011
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