Coolant leak and vapor through vents

P0430 - Catalyst System Efficiency Below Threshold (Bank 2) Indicates Bank 2 catalyst system efficiency is below the acceptable threshold.

• Use of leaded fuel
• Damaged HO2S
• Malfunctioning ECT
• High fuel pressure
• Damaged exhaust manifold
• Damaged catalytic converter
• Oil contamination
• Cylinder misfiring
• Downstream HO2S wires improperly connected
• Damaged exhaust system pipe
• Damaged muffler/tailpipe assembly
• Retarded spark timing

Compare HO2S upstream & downstream switch rate. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which makes the switching frequency of the downstream HO2S quite slow compared to the upstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal begins to switch more rapidly approaching the switching rate of the upstream HO2S. Once beyond an acceptable limit the DTC is set. Catalytic converter bad !


P0442 - EVAP Control System Leak Detected (Small Leak) The PCM monitors the complete EVAP control system for presence of a small fuel vapor leak. The system failure occurs when a fuel vapor leak from an opening as small as 1.016 mm (0.04 inch) is detected by the EVAP running loss monitor test.

• After-market EVAP hardware (such as fuel filler cap) non-conforming to required specifications
• Small holes or cuts in fuel vapor hoses/tubes
• Canister vent solenoid stays partially open on closed command
• Damaged, cross-threaded or loosely installed fuel filler cap
• Loose fuel vapor hose/tube connections to EVAP system components
• EVAP system component seals leaking (EVAP canister purge valve, fuel tank pressure sensor, canister vent solenoid, fuel vapor control valve tube assembly or fuel vapor vent valve assembly)

EVAP Leaks P0442 and P0455

The Evaporative emission system has a large leak allowing fuel vapors to escape to the atmosphere . There are hoses an a purge solenoid ,a vent solenoid ,charcoal canister to store fuel vapors in . The charcoal canister is located under the vehicle near the fuel tank an has vapor lines running to the front of the vehicle to where the engine draws in the vapors by the engine computer opening the purge solenoid ! Any of this vapor hose could have a hole (leak) ,the gas cap could be lose or bad . The fuel filler neck could be rusted through ! At the repair shop we hook up a smoke machine to the system an look for a leak like that ! easy !

Code 172 means the O2 sensor is telling the computer the fuel mixture is too rich.
Code 455 is a large evap leak in the gas tank venting system, and code 442 is for a small leak. The engine computer pressurizes the fuel tank every few minutes to check for leaks. Vapor leaks (fumes) could escape into the air if the system is not working correctly.
Its possible the system is faulty and allowing gasoline to be pulled into the engine instead of it being vented thru the vapor canister.
You would need to find out where the vent leak is first.

this is a big job and requires the whole dash taking out ,as a stop gap measure join the heater pipes together so it doesnt leak inside the car but it will be cold to drive at this time of year .

The first thing I would check is the fuel cap. Your vehicle uses a closed vent system to control the fuel vapors in the tank and then vent the vapors to the engine intake system to burn. so you have a leak either your purge/ vent solenoid is stuck or open all the time not allowing the on board diagnostics to run the test or you may a bad fuel cap, and it is venting to the atmosphere allowing the gross leak. The purge/ vent valve is under the vehicle next to the charcoal canister.

This indicates a fuel vapor leak in the EVAP control system. It means a very small 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 P0442 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)
• A small leak/hole in a fuel vapor hose/tube
• Other small leak in EVAP system
• Faulty vent o-ring seal

With a P0442, 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, or
• Inspect the EVAP system for cuts/holes in tubes/hoses

Few places to check - rubber hose under air box (requires removing the air box) and hoses connecting to EVAP system under the van on the drivers side.

This is usually a sign of a heater core that has a leak. check for low coolant level in your radiator. there is a condensate drain for the blower box, see if coolant is dripping from the drain under the truck. To make a temporary repair, after confirming leaking heater core, loop one of the heater core hoses back to the engine, bypassing the heater core. I say after confirming because the heater core hose nipples break easily when removing hoses. The smell in the cab would be a sweet smell from leaking coolant.

On a very humid day fog can be seen coming out of vents when using the AC. This would be a normal condition.

DTC P1455 - Substantial Leak or Blockage in Evaporative Emission Control System

The PCM monitors the complete EVAP control system for no purge flow, the presence of a large fuel vapor leak or multiple small fuel vapor leaks. The system failure occurs when no purge flow (attributed to fuel vapor blockages or restrictions), a large fuel vapor leak or multiple fuel vapor leaks are detected by the EVAP running loss monitor test with the engine running (but not at idle).

Check this possible causes:
After-market EVAP hardware (such as fuel filler cap) non-conforming to required specifications
Disconnected or cracked fuel EVAP canister tube, EVAP canister purge outlet tube or EVAP return tube
EVAP canister purge valve stuck closed
Damaged EVAP canister
Damaged or missing fuel filler cap
Insufficient fuel filler cap installation
Loose fuel vapor hose/tube connections to EVAP system components
Blockages or restrictions in fuel vapor hoses/tubes (items also listed under disconnections or cracks)
Fuel vapor control valve tube assembly or fuel vapor vent valve assembly blocked
Canister vent (CV) solenoid stuck open
Mechanically inoperative fuel tank pressure (FTP) sensor


Check for audible vacuum noise or significant fuel odor in the engine compartment or near the EVAP canister and fuel tank

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Possible coolant leak on hot engine parts causing it to evaporate as it leaks. That would definitely invade the cabin air. You would need to carefully check under the hood with the engine warmed up and running.

Also could be a headgasket failure between coolant channels and a combustion chamber. This latter problem sometimes shows itself as vapor at the tailpipe after there should be no more visible. You may also detect the odor of coolant there too.

Your heater core needs to be replaced. It's located on the passenger side , under the dash. The heater core is like a small radiator. Coolant from the engine is circulated through it, and that is what provides heat in the car. The heater core is leaking, causing the 'vapor' through the vents, and leaking on the carpet on the passenger side. Heater cores are a pain to remove and replace, it's quite a labor intensive job.