bank cat 2 check engine

Alkemist

Member
Joined
Jul 16, 2020
Messages
53
Reaction score
7
Points
8
I have a 2019 w 90k miles livery edition, i just had the check engine pop up with a bad cat bank 2. can the cats go bad at that mileage? any other issues that it may be, my lincoln app also says its "powertrain control system has detected that it is unable to move the active grill shutter" & "engine control system has detected that the catalytic converters efficiency is below an acceptable level." the cats are not covered by the extended warranty, if i have to change the cat, does anyone have a part number, thanks a lot!
 
Could just be an o2 sensor. What is the exact code?
 
Alkemist,
If you run a scanner and see the rear O2 sensor is switching high to low as much as the front sensor then your cat is bad for some reason. Better find out what caused it to go bad.

If back O2 sensor is switching much less than the front one your cat is good.

I suspect you are somewhere in between where the rear O2 switches less but, enough to alarm the computer. If that is the case you can install one of these on your rear O2 sensor. It will slow down the switching but, allow the sensor to continue to work.


You need to log the data to decide which direction to go.

P.S. I can't believe the EPA would let Lincoln deny a warranty repair on a catalytic converter after only 2 years....
 
You have the 3.7L?
In that case the 87 is good unless you live in Denver or higher. The higher octane will not damage the catalytic converter. 93 octane should not hurt anything except your wallet.
 
You have the 3.7L?
In that case the 87 is good unless you live in Denver or higher. The higher octane will not damage the catalytic converter. 93 octane should not hurt anything except your wallet.
Yes 3.7. Alright, i guess i will change the o2 before touching the cats, bc i cant believe theyd go bad at this mileage, everything else works perfect
 
Before buying a new O2 sensor it would be best to watch them working with a scanner. If you don't have one and are handy you should at least switch the two rear O2 sensors.

If the problem is the sensor the error code will move with it, if the problem is the cat it will stay in the same location.

If the error code moves by all means change that O2 sensor and if it stays you will need deeper diagnosis.
 
Before buying a new O2 sensor it would be best to watch them working with a scanner. If you don't have one and are handy you should at least switch the two rear O2 sensors.

If the problem is the sensor the error code will move with it, if the problem is the cat it will stay in the same location.

If the error code moves by all means change that O2 sensor and if it stays you will need deeper diagnosis.
Thats smart. I do basic work myself, had an escalade the past 20 yrs and just switched to this sedan. “Bank 2” would be the rear o2s under the car right? Anyone have a diagram?
______________________________

Help support this site so it can continue supporting you!
 
While with the scanner, check for any misfires at that bank - live or recorded.
On a Mustang, the same code was thrown due to a coil on plug going intermittently bad before it goes so bad that the diagnostics catch it. Or it could be worn out spark plug/plugs - the same effect - unburned fuel and O2 hitting the cat.*
If it is a COP/plug, then it should be easiest to provoke it at sub 2000 rpm on light uphill in higher gear. The best is 1500 rpm 35-40 mph - hard conditions with allot of swirl and thump inside the cylinder combined with high cylinder pressure.

In 2 years it's not an O2 or cat. Either injector leaking or not spraying properly, or ignition.

All suspicions can be confirmed or dismissed with live data, scanner and experienced tech.

*-> Spark plugs so worn out that they cause persistent misfire that shows up at emission system might and probably will degrade the COP's, so if that turns out to be the cause, I'd replace all 6 COP's as well.
 
Last edited:
Thats smart. I do basic work myself, had an escalade the past 20 yrs and just switched to this sedan. “Bank 2” would be the rear o2s under the car right? Anyone have a diagram?
No it is from the front bank, the bank next to the firewall is bank 1. Imagine the engine turned 90 degrees so that the battery end is next to firewall and the end with the serpentine belt is next to the grille. From the drivers perspective #1 cylinder is on the right nearest the grille.
 
I have a 2019 w 90k miles livery edition, i just had the check engine pop up with a bad cat bank 2. can the cats go bad at that mileage? any other issues that it may be, my lincoln app also says its "powertrain control system has detected that it is unable to move the active grill shutter" & "engine control system has detected that the catalytic converters efficiency is below an acceptable level." the cats are not covered by the extended warranty, if i have to change the cat, does anyone have a part number, thanks a lot!
What engine do you have? Procedures for access may differ. There are two oxygen sensors on each bank, the one closest to the cylinder head is heated so as to operate quickly and is the sensor used for the PCM to determine oxygen content to adjust injector firing. The second oxygen sensor is called the "catalyst monitor sensor" and is mounted to the catalytic converter and is used to detect the changing oxygen level through the cat by comparing oxygen level between the first heated oxygen sensor and the second oxygen sensor. The cat should make a substantial difference in oxygen levels between the two sensors.

Attached are the procedures for access to the 2.7 engine oxygen sensors. Changing the cat is not a simple job, see attachments for LH and RH cats.

I will see what I can find on the front active grill shutter.

Have you considered getting a diagnostic from your dealer, since electronic control problems (both problems) are not easy to diagnose oneself.
______________________________

Help support this site so it can continue supporting you!
 

Attachments

What engine do you have? Procedures for access may differ. There are two oxygen sensors on each bank, the one closest to the cylinder head is heated so as to operate quickly and is the sensor used for the PCM to determine oxygen content to adjust injector firing. The second oxygen sensor is called the "catalyst monitor sensor" and is mounted to the catalytic converter and is used to detect the changing oxygen level through the cat by comparing oxygen level between the first heated oxygen sensor and the second oxygen sensor. The cat should make a substantial difference in oxygen levels between the two sensors.

Attached are the procedures for access to the 2.7 engine oxygen sensors. Changing the cat is not a simple job, see attachments for LH and RH cats.

I will see what I can find on the front active grill shutter.

Have you considered getting a diagnostic from your dealer, since electronic control problems (both problems) are not easy to diagnose oneself.
wow thanks a lot! i have a 3.7l livery edition. I am hoping it is not the cat given its only 90k miles, the cat i would not change myself and have my mechanic do it.
 
@Alkemist the Active Grille shutter is not engine dependant. Attached are the descriptions and procedures of the system including: Overview, System operation, Diagnostic, Grille removal and front cover removal, Grille actuator removal (requires grille removal), etc.

I would check the electrical connections and look for any damage to the grille from stones etc. The active grille shutter is a tall unit covering the upper grille area and the lower grille area below the bumper.

Looks like a diagnosis by dealer item.
 

Attachments

@Alkemist the Active Grille shutter is not engine dependant. Attached are the descriptions and procedures of the system including: Overview, System operation, Diagnostic, Grille removal and front cover removal, Grille actuator removal (requires grille removal), etc.

I would check the electrical connections and look for any damage to the grille from stones etc. The active grille shutter is a tall unit covering the upper grille area and the lower grille area below the bumper.

Looks like a diagnosis by dealer item.
thanks again, can these possibly be related to each other? now I am wondering if the guy sold me the car because of this problem, i didnt expect much issues with this car especially with it having extended warranty but the cat isnt covered, ill see if this issue is
 
thanks again, can these possibly be related to each other? now I am wondering if the guy sold me the car because of this problem, i didnt expect much issues with this car especially with it having extended warranty but the cat isnt covered, ill see if this issue is
Not likely, but the PCM is the common denominator. There may be other modules that might be contributing. There is an emission warranty too, and that is for a longer time than bumper to bumper warranty but not sure of mileage. The above diagnostic of checking sensors may find a sensor issue rather than a Cat issue. But you could also have a wiring/connector issue.

The problem with DIY diagnostics is the inter-dependency of the systems and their modules. I would definitely check with your dealer to get a good understanding of the warranty on the car and if there is a diagnostic cost.
______________________________

Help support this site so it can continue supporting you!
 
Not likely, but the PCM is the common denominator. There may be other modules that might be contributing. There is an emission warranty too, and that is for a longer time than bumper to bumper warranty but not sure of mileage. The above diagnostic of checking sensors may find a sensor issue rather than a Cat issue. But you could also have a wiring/connector issue.

The problem with DIY diagnostics is the inter-dependency of the systems and their modules. I would definitely check with your dealer to get a good understanding of the warranty on the car and if there is a diagnostic cost.
totally understand, I will take a look tomorrow to see if any wiring is loose etc. and update in case someone else may be having a similar issue. the car runs and drives great.
 
It is important to know what codes are shown in the OBDII system. Most local (US) autopart chains will read the codes for you, if you do not have your own code reader.

On one of my Land Rovers, I found that a P1646 (a bad O2 sensor) was being set by dirty injectors causing a spitting instead of fine spray. A good fuel system cleaner (Lucas, SeaFoam, BG44K, et al) would clear it up. Still, had to reset the OBDII to remove the code. At 90K, seems way too soon for a bad cat or bad sensor.

It would be useful to know where the car is located: if the weather has turned cold, a bad Temperature sensor will also cause the ECU not to provide the correct starting stoichiometry thus over-enrichening the mixture and a false reading at the O2 sensors. On Jags, this was a common issue for hard starting, O2 and misfire codes every Fall except LA, TX, and FL.
 
Last edited:
It is important to know what codes are shown in the OBDII system. Most local (US) autopart chains will read the codes for you, if you do not have your own code reader.

On one of my Land Rovers, I found that a P1646 (a bad O2 sensor) was being set by dirty injectors causing a spitting instead of fine spray. A good fuel system cleaner (Lucas, SeaFoam, BG44K, et al) would clear it up. Still, had to reset the OBDII to remove the code. At 90K, seems way too soon for a bad cat or bad sensor.
i am going to put half a liter of chevron fuel cleaner, i spoke to the guy, he says the car was sitting for about 5-6 months, its a high end limousine company that sold it to me for 18k, brand new condition even with the miles. I am thinking it maybe bc the car was sitting for so long, and I havent driven it much, barely finished 1 tank. he said there were no issues and no cel, and i believe him. appreciate all of your help
 
Techron is good stuff. Might go to Chevron high test, as well. My brother has a 2L turbo in his MKC; he was shocked by the improved performance and gas mileage when he shifted up to higher octane. Me, nothing but high test for the last twenty cars. . . .
 
Back
Top