Codes

[VS_Pete]

Got these codes on Monday 22/05/2020 reset
U0073
Control Module Communication Bus A Off
P0420
Catalyst System Efficiency Below Threshold (Bank 1)
P0700
Transmission Control System (Mil Request)

One came back yesterday 27/05/2020
P0420
Catalyst System Efficiency Below Threshold (Bank 1)

Car is running good haven`t noticed anything.
Thoughts please. Post O2 sensor??
I just put a red A in as my scanner didn`t have it.

 

[Freedon]

how old are the o2 sensors? also check wiring and fuses

 

[VS_Pete]

3 years catback put on all 4 O2s replaced
the car is just over 70000k
Which fuses?

 

[TAS1981]

How’s the battery?

I have found that a weak battery will start setting off codes all over the place of a sensor requires a high/low voltage to read.

Engineering mode with ignition on only will give you a read in the morning to see what voltage it’s sitting at. Is it sluggish to start? How old is it? Most battery places will test it for free for load test etc. if it’s free it’s just something to rule out....

 

[Fu Manchu]

What about a trip to the wreckers for a spare o2 sensor? Chuck it on and see.

 

[Not_An_Abba_Fan]

Are you having issues or are you just scanning the car for the hell of it? Quite often codes will be set and stored as there are millions of data packages sent all over the car every day, if there is a discrepancy in any of those it will set a code, doesn't mean there is anything wrong with the car. Most random codes are to with electrical "faults", low voltage, no signal, things like that.

 

[VS_Pete]

Are you having issues or are you just scanning the car for the hell of it? Quite often codes will be set and stored as there are millions of data packages sent all over the car every day, if there is a discrepancy in any of those it will set a code, doesn't mean there is anything wrong with the car. Most random codes are to with electrical "faults", low voltage, no signal, things like that.

I don`t scan unless I have the light comes on.
Have not had the codes before so asked on here.
I reset codes both times and so far so good.
From the time I got the new car and got codes I learnt to scan and deleted codes to see if they came back.
Until I got codes up car running on 3/4 cyclinds back firing after years finely the codes were right all O2s F***ed.
I know about the battery playing up if on the way out.

I`m not going to get O2 sensors to test 5days so far no codes I`ll just do what I`ve learnt scan reset and hope for the best.

I`ll get my log out and put it up so READ IT.

Going to work car running bad made it to dealer turned car off.
They tested nothing wrong.
Runs great for 6mths slite missfire reset all good like I learnt

 

[woteva]

Missus said the engine light was on in our VE last week after starting on some very cold mornings. Heard her crank it this morning and it sounded sick. Went out and got a new battery and will see how it goes tomorrow.
The original battery had lasted 8+ years.
I haven't even bothered checking the codes as she said they only happened in the morning and I have been away for the last 2 weeks.

 

[VS_Pete]

Missus said the engine light was on in our VE last week after starting on some very cold mornings. Heard her crank it this morning and it sounded sick. Went out and got a new battery and will see how it goes tomorrow.
The original battery had lasted 8+ years.
I haven't even bothered checking the codes as she said they only happened in the morning and I have been away for the last 2 weeks.

I did the same and got a new battery when the old one played up (a while ago) didn`t look for codes eather.
You just know you need a new one

 

[Not_An_Abba_Fan]

Well, your original post didn't say anything about the car running rough, just a bunch of codes and

Car is running good haven`t noticed anything.

hence my question.