Hi, I'm looking for some suggestions for a couple of codes I've been getting recently with the post-cat Lambda Sensor:

000313 - Oxygen (Lambda) Sensor B1 S2: Response too Slow

004372 - Oxygen (Lambda) Sensor; B1 S2: Internal Resistance too High

It's an Octavia vRS 2.0 TFSI, 2007, 73,000 miles, Stage 1 remap (at around 50,000 miles), no other mods.

Both faults are consistently coming back, being logged every time the car is driven, not getting any other codes - this has been happening for about two weeks. Car feels normal when driving, no unusual idling or stuttering.

Have had a good search on here and other VAG forums, found a few mentions of these, but not many solutions. The recurring theme is people replacing the sensor, but the same error codes being logged with the new sensor too. Also, quite a few mentions of people finding oil or water in the sensor connector.

I checked my connector and indeed, found dirty water inside, so dried it out with a hair dryer, didn't see any corrosion so I've given it a light squirt of WD-40 and put it back together. Fault still being logged though.

Read some people suggesting this could be linked to the crankcase breather hose, or maybe the PCV. I've had the PCV off and it seemed to be working normally, and not found any hose damage or leaks in the air system around the engine bay.

Is there anything else worth checking that commonly causes these codes?

Many Thanks

Ross

If it's doing the same with a new sensor and you've previously found water in the connector, I'd say that the wiring inside the connector is suspect, the water could have got in where the wire is crimped to the pin. You can try removing the wires from the connector for a better inspection, or measure the wire resistance from the ECU to the connector pins, which will be a bit of work, or probe the wire before the pin so that you can measure the resistance across the pin, this will mean damaging the insulation.

Just following up for the benefit of anyone that finds themselves here with the same fault codes.  This turned out to be a faulty lambda sensor (post cat) after all.  

 

Unusual for it to pack in after only 73k, but the new sensor (around £70) and clearing the fault codes has resolved the issue (no more fault codes logged after a week - touch wood!)