I have a 2018 F-150 STX and am the original owner. It has 34K miles and the check engine light came on yesterday. I checked and the code is P0430.



A couple of months ago, my mileage dropped off about 1~2 mpg. Last month driving at speed occasionally the engine seems to slightly hesitate a few times them return to normal driving. This happens occasionally, but not all the time.



Fuel injectors need cleaned? Bad gas? Mass air sensor need cleaned?



Hoping someone can steer me to figure out what is going on. TIA.

 

catalyst system efficency below threshold. left bank

 

The rear O2 sensor is detecting that activity through the catalytic converter is not correct. Check the O2 sensor signals with a scanner to make sure they are working properly, as one could be going bad. The catalytic converter may be going bad; likely clogging with your hesitation symptom description. Catalytic converters are covered by the emissions control warranty for 8 years or 80k miles.

 

P0430 - Catalyst System Efficiency Below Threshold Bank-2

Possible Causes:

• Damaged heated oxygen sensor (HO2S)
• Exhaust leaks
• Damaged exhaust manifold
• Damaged catalytic converter
• Oil contamination
• Cylinder misfiring
• Downstream HO2S wires incorrectly connected
• Damaged exhaust system pipe
• Damaged muffler and tailpipe assembly
• Evaporative emission (EVAP) purge valve stuck open
• Leaking fuel injector
• Oil contamination of the catalyst
• Damaged turbocharger
• Base engine concerns

Diagnostic Aids:
Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which reduces the frequency and amplitude of the downstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal has an increased amplitude and frequency. The PCM compares the signal line length of the downstream HO2S to an expected signal line length of the downstream HO2S with a deteriorated catalytic converter.
Diagnose any base engine concerns.

 

Sound like the substrate in the cat has broken up and partially blocking the outlet of the cat causing high backpressure on that bank.
In that case, the Ox storage will not be high enough.
In this event the action of the rear sensor will not be correct and set the code.
All that needs to be done is look at the (rear sensor) action as compared to the good bank to see the difference. Looking for voltage swings that should really be quite stable and voltage and current drawn by the heater circuit.
Sensor 'specific' faults have their own codes.
Should be covered by warranty, if that is the fault.
Good luck.

 

Welcome to the forum.
Putting some truck info in your sig, would help site members help you..
.

 

Bad catalytic converter. Covered under an 8/80 federal warranty. Just take it to the dealer and claim your freebie.

 

Another one hit wonder who posted and never came back so far in 4 days. Must not be super concerned about the code.

 

I'd recommend getting a full OBD scan to pull current and any historical codes. Since you mentioned some hesitation, a misfire causing unburned fuel to travel through the exhaust could be the reason for the deterioration of the cat.

 

Be prepared for a long wait for a replacement if it is indeed the cat. Dealer has had new cats on order for my 19 (p0420/0430) for six months with no eta from ford.