4-4-3 cat. efficiency. Hole in exhaust the cause?

[alschnertz]

1995 854T; 258,000 miles

Is it possible that a hole in the muffler could set a 4-4-3 code?
There is also a leak at the front pipe / rear pipe connection.

Front O2 sensor was changed at 216,000 miles.
Rear O2 sensor was changed at 250,000 miles.

I haven't checked O2 sensor voltage readings since the car is not on the road.

[RickHaleParker]

Could be one of five things or a combination of two or more of the five.

1. Fuel pressure test
2. Compression test
3. Check for Intake Air leaks
4. Check for Exhaust Air leaks
5. TWC

------------------------------

28: 4-4-3 TWC efficiency. Signal faulty

DTC information 4-4-3

A2300687 Condition
The ECM continuously monitors the TWC's efficiency by comparing the signal from the rear HO2S with the signal from the front HO2S. When the TWC's efficiency deviates too much, the ECM sets DTC 4-4-3.

Substitute value
None.

Possible source

• Uneven compression.
  Air leakage in the intake system.
  Air leakage in the exhaust system.
  Incorrect fuel pressure.
  Defective TWC.

Fault symptoms
Can result in poorer performance.

[alschnertz]

Thanks.
I didn't think to check compression or fuel pressure because the car has always run well.
Haven't detected any misfires by the seat of my pants.

Your info looks thorough. Where did that come from?

[RickHaleParker]

Where did that come from?

Copy and paste from Volvo VIDA 2014D.