View Full Version : Wideband O2 sensor issues

Mad Cow
04-08-2013, 02:15 PM
I recently bought a Bosch 17014 sensor, which is apparently used in the MK4. Although the cable is shorter everything looks the same, but I'm getting a code for the sensor heater. I checked it with a multimeter and it's just under the 3 ohm minimum. Contacted the place I bought it and they said Bosch doesn't accept returns from retailers, so I'm forced to send it back myself. Being in Canada I'm going to have to pay shipping twice, plus wait at least a couple of weeks to go through Bosch, which is just bollocks. Looking at their RMA form, it seems like they really couldn't care less about their warranty policy so I'm worried I might not even get my sensor back in the end if it they refuse a new one or someone "forgets" about my RMA. Has anyone dealt with Bosch RMA's before? Would it really be worth it for an $80 sensor?

Or failing that, is it in bad form to use a resistor to bump up the resistance just a bit to get it within spec and hopefully stop throwing a code?

04-08-2013, 07:26 PM
Forgive my laziness, but what is the resistance spec?

I don't see any reason you couldn't use a resistor to alter the circuit resistance in either direction, but it would have to be capable of pretty high current (probably a ceramic load resistor).

04-08-2013, 07:45 PM
ever since i swapped over to maestro ive had sensor 1 heater fault. bought a new oem sensor code came back. ive pinned out the connector to the ecu, all had continuity didn't check resistance as I don't have specs to check with. I checked voltage reading at the connectors against Mitch's car, and had same readings. I wonder if its connected to maestro, that's been what I've been leaning towards.

04-08-2013, 09:18 PM
Rear sensor still plugged in?

EDIT: oops

Mad Cow
04-08-2013, 09:21 PM
The spec is 3 - 10 ohms, I'm getting around 2.5. I've also checked over everything, continuity to the ECU pin and ground, good voltage. If it happened after getting Maestro it could be software related, maybe there's a tolerance set somewhere. I have a stock CH box tune on a CM box, maybe that has something to do with it.

04-08-2013, 10:48 PM
post the exact code youre getting.

Mad Cow
04-09-2013, 07:22 AM
P0135, implausible signal from B1S1 heater. Isn't that the only code you can get from the heater circuit?

04-09-2013, 08:05 AM
Nope. There is:

P0135: O2 Sensor Heater Circ.,Bank1-Sensor1 Malfunction
P1115: O2 Sensor Heater Circ.,Bank1-Sensor1 Short to Ground
P1116: O2 Sensor Heater Circ.,Bank1-Sensor1 Open
P1196: O2 Sensor Heater Circ.,Bank1-Sensor1 Electrical Malfunction
P1102: O2 Sensor Heating Circ.,Bank1-Sensor1 Short to B+
P1103: O2 Sensor Heating Circ.,Bank1-Sensor1 Output too Low (performance too low)

maybe more.

04-09-2013, 08:29 AM
Ill have to check my records, but I think it was 0135

Mad Cow
04-11-2013, 09:20 AM
I tested my old sensor which gave the code too, 3 ohms. I tested my new one again but let the reading stabilize for longer and it too was 3 ohms. So now it seems my new sensor is bad, can someone measure the resistance across the 2 inside pins (3 and 4 I think) when their sensor is at room temp?

04-11-2013, 09:54 AM
I think I have my old sensor laying around at home. I'll certainly forget by tonight, but if you PM me after 8pm EST, I can get a reading for you.

04-11-2013, 12:13 PM
I can do mine tomorrow. Its the new one I bought that still throws the code. Just verify the pins forbme

04-11-2013, 01:31 PM
Got any friends with a wideband car you can swap the Jetta sensor into?

04-11-2013, 06:04 PM
Crap. I have a known good sensor here in front of me, but just realized I left my meter at work. Sigh. I'll check it at the shop in the AM.

04-12-2013, 10:48 AM
Measures 3.0 Ohms at room temp for me.

Mad Cow
04-12-2013, 01:46 PM
So I guess 3 ohms is normal, thanks for the help walky. I'm gonna take a look into the FR then, probably gonna be something useful in there.

Mad Cow
04-17-2013, 10:10 AM
With a bit of research I found that P0135 is triggered basically by time between heater activation and the sensor working. I have a feeling that it has to do with my ECU relay issue as it's making the ECU do all kinds of odd things. (no throttle cut on clutch, no SAI diagnosis, fuel trims, and a bunch of other stuff)

Here's the flowchart if anyone's interested, click for a bigger image:
http://i.imgur.com/oMe0eDbl.jpg (http://imgur.com/oMe0eDb)