Iam having exhaust gases coming out of the ac ducts

A P0420 diagnostic trouble code is a "generic" fault code that is set when the Onboard Diagnostic II (OBD II) catalyst monitor detects a drop in converter efficiency. The OBD II system monitors catalyst efficiency by comparing the switching activity of the upstream and downstream oxygen sensors in the exhaust. The upstream O2 sensor in the exhaust manifold reacts to the exhaust gases as they exit the engine. The downstream O2 sensor in or behind the catalytic converter reacts to the exhaust gases as they exit the converter.

most ECM controlled engines have an EGR (exhaust gas recirculating valve) system. It is sued to lean out mixture with inert gases ( exhaust gas)/re-burn exhaust gases to meet pollution requirements.

Thermostat? engine cooling?
2 engines, here, LYA adn LY7.
nobody here posts engine, why do that?
so ill post only for 1.
the LA1
here are the steps.
NO FSM Sux huh? nor an alldata.com account, why not that? 15 bucks?


STAT out.
Remove the air cleaner and duct assembly. Refer to Air Cleaner Assembly Replacement in Engine Controls - 3.4L.

Drain the coolant until the coolant level is below the thermostat. Refer to Cooling System Draining and Filling (Refer To List 1) .

Remove the crossover exhaust pipe. Refer to Exhaust Crossover Pipe Replacement (Refer To List 2) in Engine Exhaust.

Remove the radiator hose from the thermostat housing.

Remove the thermostat housing bolts and clean any sealer from the bolt threads.

Remove the thermostat housing and gasket.
remove STAT
next is crossover page.

Disconnect the battery ground (negative) cable. Refer to Battery Negative Cable Disconnection and Connection (Refer To List 1) in Engine Electrical.

Remove the throttle body air inlet duct.

Drain the coolant from the cooling system. Refer to Cooling System Draining and Filling (Refer To List 2) in Engine Cooling.

Remove the inlet radiator hose from the engine. Refer to Radiator Inlet Hose Replacement (Refer To List 3) in Engine Cooling.

Remove the thermostat bypass pipe. Refer to Thermostat Bypass Pipes Replacement in Engine Cooling.



Remove the exhaust crossover heat shield bolts.

Remove the exhaust crossover heat shield.

1. Remove the exhaust crossover pipe studs/nuts.
2. Remove the exhaust crossover pipe.

end , remove.

now the bypass pipe FWD cars SUCK

1. Disconnect the left engine mount strut from the engine.
2. Remove the heater hose from the bypass pipe.
3. Remove the thermostat bypass pipe to throttle body nut.
4. Use the J 38185 in order to remove the thermostat bypass pipe hose clamps (1,5).
5. Remove the thermostat bypass pipe to cylinder head nut (3).
6. Remove the thermostat bypass pipe bolt (4).
7. Remove the thermostat bypass pipe hose.
8. Remove the thermostat bypass pipe.

sigh.....
why not log in to alldata.com
read the page then ask ques tons that are not clear.
and next time post the engine type.
above is just 1 engine.

EGR is exhaust gas recirculation valve. Its works kind of turbo chargers sometimes egr takes some of still fuel rich exhaust gases and injects in intake back order to save some gas and cleaner exhaust gases for environment You should locate your exhaust manifold and fallow smaller size piping coming out of it one of that pipe goes Egr

Your compressor lines could be frozen so gases will not be doing there job. Or possibly you have leaking duct work. Does it feel hot in every room or just in a few. If it is just certain rooms your duct work has come apart some where in attic

is the check engine light on ! if so it may be a clogged up convertor. here is the symtoms, A clogged catalytic converter reduces the flow of a vehicle's exhaust by creating a constricted and/or blocked exhaust channel, which engine exhaust gases flow through on their way out of a vehicle's tail pipe. By reducing the flow of exiting engine exhaust gases, a condition that creates an increase in engine exhaust back pressure (thereby reducing engine efficiency), a clogged catalytic converter results in a small reduction in engine horsepower. A clogged catalytic converter causes a reduction in vehicle gas mileage.
Fumes leaving exhaust is sulfurous as if it is coming from a rotten-egg is one of the unmistakable clogged catalytic converter symptoms. good-day !

have it pressured checked for leaks.









TIM............

EGR stands for Exhaust Gas Recirculation- It allows gases from the exhaust to mix with the intake to allow NOx gases to not form at high temperatures.

Problems with it include being plugged, or open or not holding vacuum, causing a vacuum leak.

the fan coming on is a switch which is easly fixed ,but the white smoke is water thats for sure ,iam wondering in the ac condensate drain pipe is somehow running into the inlet air intake ---how i honestly dont know as in all truthfulness iam in spain so never seen under the bonnet of one.How its laid out and all that so you will have to have a look yourself and see if iam right

exhaust recirculation helps with nox when you go through emissions