Stumble on accel on highway, fault P2240

that is not the OEM makers statement on P0401.
truth is this. V6 engine? 3.3L and 3.5L???????
o2 sensor circuit no activity detected bank 1 sensor 2)
means the right rear 02 sensor reads dead.

right bank down stream 02 is dead.

and has zero to to with rich or lean, it is the rear sensor 2.
the rear sensors are only to this bank1 CAT for good quality.
not told at all , what engine is there. v6 sure,3.3 or 3.5L
nor how the engine runs and car drives. ?
or if this is ONLY a smog question and check engine lamp glows?
causes of 401 are
wires to right rear 02 cut burned or damaged , loose or fell off 02.
bad o2 B1,S2 rear of cat bad
bad CAT bank1,
exhaust cracks in CAT sucking air and making any 02 sensor to read dead, near it.
this post ASSUMES , no other DTC errors stored or live running,
assumes scanned LTFT PID reads correctly and no B1S1 02 errors.(front sensor)
bank 1 or B1 is right front engine bank. (drivers view)
facing engine is left bank. (workers viewed)
ASSSMEs car is driven plenty not just parked in an old barn.
A DRIVEN CAR !

SMog tests fail too for monitor cat bank1 dead.
or incomplete status on bank1 cat.

EGR is stuck open, but a flashing engine light can be a misfire code also detecting a rich condition, right back to the egr.

Are you sure it's 02 sensors? Just because code says 02 sensors doesn't necessarily mean they're bad. Bad 02 sensor code can also indicate bad cat. converter. If 02 sensors read exact same reading before and after converter they will trigger OBC to "sensor fault" - they should be reading 2 different readings. (Pre CAT/POST cat) I'd suggest replacing cat converter before replacing sensors.

A code P0300 may mean that one or more of the following has happened:
* Faulty spark plugs or wires
* Faulty coil (pack)
* Faulty oxygen sensor(s)
* Faulty fuel injector(s)
* Burned exhaust valve
* Faulty catalytic converter(s)
* Stuck/blocked EGR valve / passages
* Faulty camshaft position sensor
* Defective computer

Possible Solutions:
* If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
* If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

Hope helps (remember to rate this).

simple test to know if the catalytic converter is clogged. Only a clogged cat could cause this kind of issue,, so as you try to go faster the problem would get worse because the presuure would have no way out. So to test a clogged cat you unplug the oxygen sensor and put in a pressure gauge. Ask the mechanic if he did this and if the pressure was well above 3psi. For you to have issues right off the line the pressure would have to be around 15 to 30 psi as soon as he reved up the motor. Or if you unplug the 02 sensor from the exhaust and drive the car and still have the same problem then the cat is not the cause. By creating a hole before the catalytic converter this allows the pressure out and if the cat was clogged the car should run better.
Personally I suspect you need spark plugs, or spark plug wires, or possibly a coil, or you may even have a clogged injector. Your discription of the symptom sounds like an ignition issue. If it only stumbles on accel but runs smooth at higer cruising speeds I would suspect possble a vacuum leak at the intake gasket or possible a clogged injector.

My point here is before you replace a catalytiic for a drivability issue only, you have to have excessive backpressure to cuase a drivability concern. Even if a catalytic was old and worn out and did not clean up any pollutants, which is its main purpose, the car would still drive just fine. It would just polute.

A P0303 code means that the the car's computer has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #3.

Symptoms may include:

• the engine may be harder to start
• the engine may stumble / stumble, and/or hesitate
• other symptoms may also be present

A code P0303 may mean that one or more of the following has happened:

• Faulty spark plug or wire
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector
• Burned exhaust valve
• Faulty catalytic converter(s)
• Running out of fuel
• Poor compression
• Defective computer

If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs).

Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced.

You may have a rear 02 sensor problem, but a repair shop will need to confirm it.

Accelerating and going nowhere? Might need a new cat (catalytic converter).

Could be caused by a few different thing's ,dirty mass air flow sensor ( if your vehicle has one ) A worn TPS - throttle position sensor , dirty throttle plate .

This is an O2 code, I have been told by a BMW tech that poor quality fuel can cause this as well as a dirty fuel filter which causes a slight loss of pressure and a stumble, I would do this, change the fuel filter, clean the MAF sensor for good measure and switch brands of fuel, otherwise a trip to the dealer may be in your future, average cost to repair this is about $250.00