P0141 error code with CABE engine

[KylesAudi2012]

Good evening all.

I have a P0141 error code. Heating element on the second 02 sensor isn't working. The element is working on the sensor, used a test light on the 2 power wires feeding the sensor. Have main power on the first wire but the second wire I have no power/pulse coming from ECM. Looked online for the relay location but I cannot find. I don't recall if the cover for the relays under the ECM has information. Pointers?
Thank you

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[KylesAudi2012]

Good evening all.

I have a P0141 error code. Heating element on the second 02 sensor isn't working. The element is working on the sensor, used a test light on the 2 power wires feeding the sensor. Have main power on the first wire but the second wire I have no power/pulse coming from ECM. Looked online for the relay location but I cannot find. I don't recall if the cover for the relays under the ECM has information. Pointers?
Thank you

Sent from my SM-G935W8 using Audizine Forum mobile app

Bump

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[Smac770]

Should always specify if the vehicle is B8.0 or B8.5. NAR Q5 CAEB should mean it's MY11 or MY12, both B8.0; but no reason to make us have to wonder.

CAEB 2.0 TFSI engine.

P0141 - O2 Heater Circuit (Bank 1, Sensor 2) out of range
Heater resistance, 810...4560 Ω


When reading the Audi docs, understand most everything has a component identifier associated with it to make discussing things easier.

G39 - 6-pin lambda sensor pre-cat
Z19 - heater circuit for G39, 12v on pin 4 to ECM ground on pin 3

G130 - 4-pin jump sensor post-cat
Z29 - heater circuit for G130, 12v on pin 1 to ECM ground on pin 2

The 12v for both heaters comes from fuse 10 in the ECM box. When the ECM wants to activate the heater, it connects ground to the ground pin, creating a complete circuit. Current flows, heater heats up.


So start by confirming 12v measurement between pin 4 on the lambda sensor's harness connector to the negative jump start post. And between pin 1 on the jump sensor's harness connector to the negative jump start post. You'll need at least ignition on for this fuse to be powered; I don't know if you'll actually need engine running for it to be powered.

But the idea is to see if you're getting 12v to both, or just to one, or to neither (when you know fuse 10 is powered).

While you're there, measure the resistance of the Z29 heater circuit, pin 1 and 2 on the sensor plug. At "room temp", it should be something between 2 and 14 Ω.

If this all seems fine, then with the engine started, measure the voltage between pin 1 and pin 2 on the harness plug. Are you reading "12v" (should be 13 or 14 v engine running)? If the voltage drop is present, and the sensor resistance is reasonable, there should be a working current flow. But maybe as the circuit heats up, it's not changing resistance as expected. This the resistance range in the P code spec. You can't use a meter to do a resistance measurement on an active circuit.

If you clear codes and turn off ignition and then turn it back on, how soon does this code come back? Ignition on, before even starting the engine? Immediately after starting the engine? A few minutes in, a few days eventually, ...?


The post-cat jump sensor is Bosch 16002. Wow, that's a pretty wide range of pricing out there. But seems centered around $100. If the 12v at the pin 1 is good, and 12v from pin 1 to pin 2 is good engine on, I'd just replace the sensor and see where it goes.