- My model of MX-5 is: NB/Mk2, Euphonic (2004)
- I’m based near: March, Cambs, PE15
- I’m looking for technical help or recommendations on: OBD codes/exhaust & rust repairs
Hello all,
I have two Mazda MX5s, both MOT fails; mainly but not solely on account of the dreaded rust.
The one I’ve been running most recently (KG04 UWM) has several OSB engine codes. Here they all are, along with the on-screen descriptionscrom my little diagnostic doodad:
P0031 - Heater control Circuit low Bank 1 Sensor 1
P0134 - Sensor circuit no activity detected Bank 1 Sensor 1
P0171 - System too lean Bank 1
P0420 - Catalyst system efficiency below threshold Bank 1
P1170 - Manufacturer control
I’ve googled all of the above. And TBH found what I discovered all quite confusing and bewildering.
KG04 UWM had a new clutch and CAT fitted by Four Paw Racing not long ago. I’d also asked them to replace ALL the exhaust, as it was occasionally rattling towards the rear end.
However, in the end 4Paw only fitted the clutch and the CAT, and didn’t do the rest of the exhaust (apparently the labour required to get the manifold off was such that my budget was consumed by that). I was unhappy about this, but didn’t say anything at the time. Should I have? It seems all these error codes centre around sensors near (sensor 1 bank 1, for example) or around the CAT. Am I right in this?
However, I’ve also read that it might be something to do with the ‘knock sensor’. I’ve googled replacing the latter, and learned they often melt/fail. But, and despite lots of looking, I can’t even see or find the damn thing, within the engine compartment, never mind attempt to replace it (which, judging by several YT vids I’ve watched, is a tricky job)!
So, I’ve got two dead MX5s, and I’m at my wits end! Can anyone point me in the direction of anybody that can help?
I need to understand the OBD codes better (when I explore them individually I only get more confused, tbh, as it all seems quite specialised and complex), for starters. Five codes seems rather worrying. I cleared them. But the engine light is back on.
The garage I use to do my MOTs - imaginatively called The Garage - has quoted £800 to fix the rust and replace the exhaust. But they say, rather ominously, that after all that they’ll see if the emissions are ok.
Having only just spent £1k on clutch and CAT replacement, the prospect of another £800+ is pretty scary and off putting.
I’d appreciate any useful pointers/helpful feedback. My MX5(s) are my only wheels; without them I can’t earn a living!
Thanks,
Seb