Code p0455 & p0422
DTC P0422 - Main Catalyst Efficiency Below Threshold (Bank 1)
A vehicles' catalytic converter (catalyst) helps improve tailpipe emissions by oxygenating the exhaust gasses. It helps convert hydrocarbons (HC), Carbon Monoxide (CO), and oxides of Nitrogen (NOx) into water vapor (H20), Carbon Dioxide (CO2), and Nitrogen (N).
The PCM (Powertrain control module) monitors the catalyst efficiency by means of a post-catalyst Oxygen sensor. This sensor is used primarily for this purpose. It should switch much slower than the front oxygen sensors. If at any point the PCM detects that the post-catalyst o2 sensor is switching too rapidly (indicating no change between the inlet and outlet of the catalytic converter) it interprets this as a catalyst that isn't functioning properly.
Bank 2 is the side of the engine that has cylinder #1.
Symptoms of a P0422 DTC may include:
Increased tailpipe emissions
MIL (Malfunction Indicator Lamp) illumination
Potential causes of a P0422 code include:
Bad or non-functional catalyst
Engine operating out of optimal air:fuel ratio
Catalytic converters contain precious metals like platinum, palladium, rhodium among others. Basically, the cheaper the cat, the less precious metals used. It should be noted that there are some automobile makes that are very finicky when it comes to catalytic converters and the logic that the PCM uses to monitor them. Just because the parts guy says it will work doesn't mean that it will. The reason is that the engineering of the vehicle was done with a high quality catalyst in mind and it can't be replaced with a low cost catalyst. There are also different kinds of catalysts. Some makes will allow for a cheaper catalyst while others simply will not. Toyotas & Subarus are the most notorious for this. Subarus require CARB certified catalysts to keep the check engine light off and won't tolerate an aftermarket catalyst, no matter how expensive.
So basically if you have a recurrence of this code after replacing the catalyst with an aftermarket catalyst, this may be your problem. If you have this code and haven't replaced the cat, there's basically two likely causes: The catalyst is no good, or the engine is running out of optimal air:fuel ratio. A tune up or engine repair may correct it. Otherwise you'll need to replace the catalyst.
DTC P0455 - Evaporative Emission Control System Leak Detected (no purge flow or large leak)
This indicates a fuel vapor leak or lack of purge flow in the EVAP control system. It means a large leak has been detected. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.
A code p0455 most likely means one or more of the following has happened:
A loose or improperly affixed gas cap
A non-conforming gas cap (i.e. not factory/original brand)
Other leak or damaged piece in EVAP system
Possible Solutions: with a p0455, the most common repair is to:
Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
Otherwise, replace the gas cap, and/or
Inspect the EVAP system for cuts/holes in tubes/hoses (you may hear a vacuum noise or smell fuel), repair if necessary
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Jul 12, 2012 |
2003 Dodge Dakota Club Cab