Rx-S6

Check engine light on. The car is running OK. Here are the codes.
16538 no activity 02sb2s1 intermitent
17605 o2 sensor heater b2s1
malfunction intermitent.
What do I need to replace?
thanks,
Dave

PaulW

Do you have the Bently? If so, just open up the fault code table under fuel injection, then it tells you to go to measuring blocks, read the voltage of the 02 sensor and the resistance values....

Then you go from there. It looks very easy and straight forward.

Rx-S6

I've got the bentley on cd for my 95.5 S6. Will that help?

PaulW

What car has these codes? An A8? If so, no the S6 Bently won't help

Cjshutts

You need to check the Bentley code list to see which o2 sensor this error refers to. The A8 has four. My problem was the two after cat sensors (both heated).

The O2 sensor you show here has a heater, so the connector to the sensor has four wires two for o2 signal and 2 for the heater. This would lead me to believe the connector has loosed since you have errors on both sides.

Also heated o2 sensors have fused heater circuits, so there is a fuse worth checking, on the A8 it is ST4 or ST3 (I forget) in the blue buss panel.

In my car's case I needed a new section of wiring harness.

So, if the fues is good, unplug the o2 sensor, turn on the ingition and check for voltage on the heater side of the connector. If you have voltage check the resistance of the o2 heater, it should be 2-5 ohms (check this, it is a few ohms anyway), and will change as it heats up.

So if the resistance is zero it is a bad sensor, if the voltage is zero, check the fuse and the wiring up to the ECM. On the A8 the ECM sends power to the fuel pump relay which turns on the heater when the ignition is on. The ECM then measures heater current on the ground side of the o2 heater. Good luck.

GDJT Allroad^2

<ul><li><a href="http://www.bentleypublishers.com/tech/audi/audi.dtc.table.htm">General codes from Bentley...</a></li></ul>