Car just died "operation too low P0420"

[1.6mk4GOLF16v]

Started perfect, about to take off n i hear a chewing kinda noise like something was hitting/cracking under the car
Seconds later it stopped and didnt start again, turns over fine like she wants to start but never did
Got the AA to tow it home n did a quick scan on his SnapOn kit
Code that came up was:

Cylinder bank 1 efficiency 16804
Operation too low P0420

She has had a de-cat job done so i usually have the engine management light on anyway, with the "Cylinder bank" fault code but i do, do regular scans, its the secong half of the fault (P0420) that ive never seen before

Any suggestions where to start guys? gonna do a quick search on the forum now

[topher]

16804 and P0420 are the same code, just one is manufacturer specific and one is obd generic.

[1.6mk4GOLF16v]

The AA guy who picked it up said it could be the sensor near the crankshaft, mean anything to you?

With the codes that ive put what would you suggest where i start mate?

[1.6mk4GOLF16v]

Anyone?

[MK3TDi1996]

The crank sensor.  I'm a mk3 man myself but it's the same thing really.

Just a little sensor to tell the ecu where the crank rotation is at.  It will indeed prevent it from starting aye.  Check your wiring to it and if it all seems well then unbolt the sensor from the block and see if it is covered in sh*t (clean if so) or seek out a replacement sensor...

[1.6mk4GOLF16v]

turned out the timing belt broke (ouch) couple of valves bent aswell!  :embarassed:

£600 to sort the valves and skim the head etc and have it working perfectly

VW garage quoted £1295