Can 02 sensor CEL cause immobiliser/ignition faults?
 

Hi all,

Recently, my car has thrown my a CEL (P0031) 02 sensor issue.
However, at the same time - it's having immobiliser issues, like it'll let me in and turn ignition on and prime the fuel pump, but it's intermittent in letting me actually start. Sometimes it'll take a couple of attempts, but yesterday it stranded my at the hospital for 35 minutes until it let me start.... which isn't ideal haha.

I'm taking a guess in that one problem has caused the second? Car electronics really are not my strong point though!

Cheers.

Hey,
First things first have your immobiliser removed :) I too have been stranded by a faulty immobiliser and I had it removed on my 1993 WRX (aftermarket).

There are many things which could be causing your issue. But if your battery is strong, and alternator working correctly I doubt they would be related. Make sure there is no water or condensation in your fuse boxes. Try testing the battery first, weak batteries can cause weird issues!

Might be unrelated, but a lot of people have reported issues with immobilisers when parked up near radio masts, often those used by hospitals. The frequencies used must overlap with those used by Subaru.

I've never had the problem but i've read numerous posts over the years by people... as they say, there's no smoke without fire...

Google 'subaru immobiliser radio mast' and have a read.

Thanks for the replies, I'll do some homework on it.

I had a feeling it was unrelated to the CEL, but both problems appeared at exactly the same time - which was nice of it!

Can also be dirty contacts on the relay that cuts the ignition circuit in the immobiliser or even burnt tracks resulting in dry joints.

https://live.staticflickr.com/1753/4...784d511a_b.jpg

https://live.staticflickr.com/1789/4...b98962ab31.jpg

Would that be the relay in the fusebox under the bonnet? I have a sneaky feeling something has got a little damp and is causing issues, rather than interference from masts.

Sometimes, I have to hold the key in the 2nd position and there's a delay before it'll fire up.

That's the circuit board out of the Sigma Alarm module, not sure where it lives in a newage. Worth checking all the earths, my main earth from the battery to the engine/gearbox was quite corroded. If your battery is getting low or the terminals are dirty putting a load on the battery like trying to start the car can upset the alarm module as the voltage drop effectively drops power to the alarm, the relay opens and the starter won't engage.