so i was letting my car warm up for a minute after work and just before i went to shift in to gear and leave the parking lot, my CEL comes on.

this was on like wed/Thursday, but i had to get my oil changed anyways so today i brought it in.
and not to my surprise its kinda what i thought it would be, o2 sensor.

anyways they ran codes (this is an audi/euro shop)
so my codes read as follows ;


16795 - secondary air injection system: incorrect flow detected
p0411 - 35-10 intermittent

1602 - engine coolant temp. sensor (g62): signal too high
p0118 - 35-10 intermittent

17521 - oxygen (lambda) sensor; B1 S1: internal resistance too high
p1113 - 35-10 intermittent

that's exactly how its typed on my paper so i thought id just include all the extra numbers etc.

the temp sensor doesn't worry me at all cuz its cheap, and from my understanding, isn't a terribly hard replacement.

the 02 sensor, from what i understand, is relatively easy, because i think its in/near the MAF? and i figure the 02 is also throwing the first code.

so the reason for this post is, i was wondering if there is anything i could check/clean/etc. to make sure its the sensor before throwing out 170+/- on an 02 sensor if i dont need it? and get any clarification on any/all codes shown above.

checking ecs, it looks like only about $200 to replace these sensors if i do it myself.
for a little background info, i dont when the last time is the air filter has been replaced i do intend on doing that, and was curious if this may have something to do with any of the codes? also its a 2000 1.8t ATW quattro manual. with 101,500miles on it. tbelt/thermo/water pump replaced at about 100,100miles.

 

Many folks had problems with the secondary air injection system. This is what Ross-Tech says:
16795 - secondary air injection system: incorrect flow detected
Fuel Pump Relay (J17) faulty
Hoses/Pipes to/between Components faulty/clogged
Secondary Air Injection Pump (V101) faulty
Secondary Air Injection Pump Relay (J299) faulty
Secondary Air Injection Solenoid Valve (N112) faulty

So start by checking for vacuum leaks, then the solenoid valve and if you don't have any problems go towards the relay and the pump in the end.

17521 - oxygen (lambda) sensor; B1 S1: internal resistance too high
The oxygen sensor is not close to the MAF, that is the Intake Air Temperature sensor. You have 4 O2 sensors, 2 before the cats and 2 after the cats. You should replace the one before the cat, located on bank 1. Of course, there can also be a wiring problem but you will have to check that yourself. A bad O2 sensor can decrease your gas mileage and cut the engine's power.

You should change the air filter once in every 10k miles because a dirty air filter can make your MAF die because of the dust that goes through and gets on the MAF's internal sensor.

 

Ok so, this kinda goes with the vac leak idea, could the possible cause of this be from A) bad DV? Or B) turbo needing a rebuild? Also, all 3 codes popped up at once, I never had any codes and this happened with a week or so after my tbelt job, so could 1 cuplrit (I.e. Vac leak) be the cause of all 3 codes? Could 1 problem cause other problems, thus popping more codes? Or could it just be a huge coincidence?

And in case anyone was wondering, yes I kno for a fact I had 0 codes cuz I ran my car computer on it multiple times after tbelt job, its a $1000+ portable computer so its pretty reliable.

 

I don't know if all 3 codes were triggered when changing your t-belt but all of them say "Intermittent" so maybe it's just a wiring issue or the guy that worked on your car made a mistake and a high voltage got into your electric system and damaged your components.
Did you try to delete the codes and scan the car again?
No, none of these 3 codes can't cause the other 2 show up.

 

Hey sorry, been gone for a while, I went up north ended up at a party and got stabbed twice so I haven't had a chance to take a look at my car. However I did notice I developed a bit of an exhaust leak thinkin that at least the o2 sensor Is the cause of that code. typical spot, right under the shifter.

 

whaaaaa???!!!

 

Ya exhaust leaks suck...