Engine: 70: P0420 Catalyst System Efficiency Below Threshold (Bank 1)

[GreenBrick]

Okay, just when I thought I was out of the woods with this car, it throws up an error code P0240.

I cleared it, and it didn't come back on a short journey, but what should I start looking at?

I looked at the voltages back from the 2 o2 sensors, but couldn't make too much sense (no pun intended) of the readings.

I guess looking at the plugs first would be a good start, in case one is rich, from a leaking injector etc?

It passed its MOT a couple on months ago, and there have been no misfires logged, and it seems to run okay, the only thing I did notice is a strong petrol smell from the exhaust when starting from cold (on a hot day) last week.

Any advice would be welcome.

[Joe H]

Originally Posted by GreenBrick

Okay, just when I thought I was out of the woods with this car, it throws up an error code P0240.
I cleared it, and it didn't come back on a short journey, but what should I start looking at?
Any advice would be welcome.

I look forward to informed comments about this as our Phase 1 car throws a similar code every 2000 miles or so.
The Indy we use says ignore it, the Cat is just getting less efficient but still fine.
It passes the MOT emissions with no trouble, and must have done 30,000 m since it first appeared.

Joe

[GreenBrick]

Right, a bit more information.

It has now happened 3 times, always the same conditions.

Warm day.
Long drive.
Stop for a short time (<20 mins)
Start engine.
Slight smell petrol from exhaust, engine a bit rough, then fine.
CEL comes on.

Should I do the obvious and change the plugs, not been done since I have owned it?

I haven't done a VIDA code read (yet, but will do), just an OBDII one.