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Purge valve and all 4 O2 sensors bad?

Purge valve and all 4 O2 sensors bad? Topic: New computer case smell
June 16, 2019 / By Elric
Question: I bought a 2001 Ford Escape XLT 4x4 80,000 miles, has been parked 3-4 years. Engine light says all four O2 sensors need replaced and purge valve is bad...and yes replaced I took it to a mechanic and had it checked. The same mechanic also said that it was probably the catalytic convertors (it has 3) We replaced the purge valve since it did have a hose broken off (got one from a junk yard). My dad who is also a mechanice but of a different sort (ATV's etc...) and has a lot of experience with repairs says there is no way the catalytic convertors are clogged that it is putting out way too much exhaust to be clogged and that there is no smell and the convertors are red. I have actually had 3 other people tell me this as well. Any suggestions? should we try a new purge valve and all new O2 sensors? would the purge valve be causing the O2 sensors to show up as bad? anything else that may be causing this? HELP!!! to replace the cat convertors is over $2000. Sorry...the convertors are NOT red...which I am told is a common sign of them being clogged. I took it to Autozone as well as a Mechanic and they both told me all four O2 sensors were showing bad...I will see if I still have the print outs for the codes ok...we went up and checked the codes again at Autozone after replacing the purge valve, this time with a brand new one. P0443, P0135, P0141, P0155, and P0161 are the codes coming up...keep in mind we just replaced the purge valve. Thanks!
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Best Answers: Purge valve and all 4 O2 sensors bad?

Clare Clare | 3 days ago
It's highly unlikely that all 4 of your O2 sensors are bad. I would have the vehicle scanned at Autozone or other auto parts store and see what comes up. Under normal use, converters are engineered to last upwards of 150,000 miles. But any number of things can make it fail prematurely. The most common cause is contamination of the catalyst because the engine is burning oil or leaking coolant internally (leaky head gasket or a crack in a combustion chamber or cylinder). Converters can also be damaged if they overheat due to ignition misfiring that allows unburned fuel to pass through into the exhaust (check for a fouled spark plug or bad plug wire). The same thing can happen if the engine has a bad exhaust valve that leaks compression into the exhaust (check compression). If the downstream O2 sensor is bad (heater circuit not working, loose or corroded wiring connector, contaminated sensor element, etc.), the OBD II system should detect the fault and set an oxygen sensor code. The same goes for a bad upstream O2 sensor. In either case, the presence of an O2 sensor code should prevent the catalyst monitor from running and setting a false P0420 code. Of course, this is ideally speaking and nothing is ever ideal. Sometimes a faulty O2 sensor is not bad enough to set an O2 sensor code but is off just enough to affect the accuracy of the catalyst monitor. To minimize this risk, it's a good idea to check the operation of the O2 sensors with a scan tool or scanner software. You should see normal switching activity in both sensors shortly after the engine is started, with the O2 sensor voltage switching back and forth between rich (over 0.8 volts) and lean (less than 0.3 volts). A flat line O2 sensor reading or one that shows little switching activity is a bad sign. The downstream O2 sensor should slow down and go flat when the converter lights off (if the catalyst is working). If it keeps on switching like the upstream sensor, it tells you the catalyst is probably bad and the converter needs to be replaced. Yes if you don't smell unburned fuel in the exhaust, the converter is working. If there doesn't seem to be a restriction in the exhaust system, the converter is working. If the converter is cherry red while in operation, the converter is working. Edit: The average temperature an exhaust system operates under is 1,200 to 1,600 degrees Fahrenheit. The internal structure of the converter is made of platinum and palladium honeycomb that filters and chemically alters the exhaust emissions. As pollutants increase in the exhaust, so does the operating temperature of the internal structure. At 2,000 degrees Fahrenheit, the structure will begin to weaken or melt, reducing its efficiency to convert harmful gases into less harmful pollutants. The platinum and palladium honeycomb will begin to melt into the ceramic substrate. When this occurs, the structure can break down or clog the converter, which results in little to no back pressure flow through the converter. The oxygen sensor will fail to register the efficiency of the converter and transmit the communication to the computer of the vehicle. In addition, little to no back pressure will result in a poor-performing engine. When exhaust is prohibited from exiting the combustion engine properly, it will choke on its own exhaust or stop altogether.
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Clare Originally Answered: Purge valve and all 4 O2 sensors bad?
It's highly unlikely that all 4 of your O2 sensors are bad. I would have the vehicle scanned at Autozone or other auto parts store and see what comes up. Under normal use, converters are engineered to last upwards of 150,000 miles. But any number of things can make it fail prematurely. The most common cause is contamination of the catalyst because the engine is burning oil or leaking coolant internally (leaky head gasket or a crack in a combustion chamber or cylinder). Converters can also be damaged if they overheat due to ignition misfiring that allows unburned fuel to pass through into the exhaust (check for a fouled spark plug or bad plug wire). The same thing can happen if the engine has a bad exhaust valve that leaks compression into the exhaust (check compression). If the downstream O2 sensor is bad (heater circuit not working, loose or corroded wiring connector, contaminated sensor element, etc.), the OBD II system should detect the fault and set an oxygen sensor code. The same goes for a bad upstream O2 sensor. In either case, the presence of an O2 sensor code should prevent the catalyst monitor from running and setting a false P0420 code. Of course, this is ideally speaking and nothing is ever ideal. Sometimes a faulty O2 sensor is not bad enough to set an O2 sensor code but is off just enough to affect the accuracy of the catalyst monitor. To minimize this risk, it's a good idea to check the operation of the O2 sensors with a scan tool or scanner software. You should see normal switching activity in both sensors shortly after the engine is started, with the O2 sensor voltage switching back and forth between rich (over 0.8 volts) and lean (less than 0.3 volts). A flat line O2 sensor reading or one that shows little switching activity is a bad sign. The downstream O2 sensor should slow down and go flat when the converter lights off (if the catalyst is working). If it keeps on switching like the upstream sensor, it tells you the catalyst is probably bad and the converter needs to be replaced. Yes if you don't smell unburned fuel in the exhaust, the converter is working. If there doesn't seem to be a restriction in the exhaust system, the converter is working. If the converter is cherry red while in operation, the converter is working. Edit: The average temperature an exhaust system operates under is 1,200 to 1,600 degrees Fahrenheit. The internal structure of the converter is made of platinum and palladium honeycomb that filters and chemically alters the exhaust emissions. As pollutants increase in the exhaust, so does the operating temperature of the internal structure. At 2,000 degrees Fahrenheit, the structure will begin to weaken or melt, reducing its efficiency to convert harmful gases into less harmful pollutants. The platinum and palladium honeycomb will begin to melt into the ceramic substrate. When this occurs, the structure can break down or clog the converter, which results in little to no back pressure flow through the converter. The oxygen sensor will fail to register the efficiency of the converter and transmit the communication to the computer of the vehicle. In addition, little to no back pressure will result in a poor-performing engine. When exhaust is prohibited from exiting the combustion engine properly, it will choke on its own exhaust or stop altogether.
Clare Originally Answered: Purge valve and all 4 O2 sensors bad?
Usually, when the O2 sensors are sending an error code, it is something else causing it, such as a lean or rich fuel condition. It would be helpful to know the codes. Just a shot in the dark would indicate a major tune up. This may cure all of the problem codes.

Ammiel Ammiel
Usually, when the O2 sensors are sending an error code, it is something else causing it, such as a lean or rich fuel condition. It would be helpful to know the codes. Just a shot in the dark would indicate a major tune up. This may cure all of the problem codes.
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Ammiel Originally Answered: Problem with sprinkler system valve.?
If there's water going through the valve when it's in the off state, the valve seat or seal must be worn or damaged. If it's the valve seat, you'll likely have to replace the valve. When you say "manually run each [station] and blow out the water", are you using compressed air? Otherwise, it's not clear how running water would blow out the water. In any case, if the valve in question opens, it should allow for your blowing out process, and if the water is shut off completely at the valve, no water should get in to refill the pipes.
Ammiel Originally Answered: Problem with sprinkler system valve.?
You didn't mention who manufactured the valve. Sounds like you have a small stone caught between the valve body and the diaphragm. Diaphragms don't open that much and a large enough piece of debris can get caught. Also some valves are manufactured with a small tick screen that is inserted into the diaphragm itself. If it comes out then there will be a small hole in the diaphragm, causing leakage. Take the entire top off of the valve body and inspect the diaphragm. Be careful of the spring in the top. If it was a stone, you will see an indentation in the diaphragm. Feel around the seating edge to see if it is damaged. If all is OK, just put it back together, if not, take the diaphragm to a sprinkler place and get a new one.

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