Hello everyone! For the past month I've went into a rabbit hole to try and figure out why my car has been running like **** and when I say **** I mean rough idle gas consumption ~1.5-2+l/h on idle when driving and the car is cold it stutters and losses boost and boosts again rapidly. I've fixed a hose that was split open after the n249 (or whatever it's called) and right before the Y split, and the PCV hose after the Y split that connects to the engine. I was hoping that these fixes solved my problem but unfortunately they didn't. These codes still persist. Also almost the same time that these problems started I wired an amplifier and the positive wire I fished it though the gormet below the steering wheel (could I have damaged any wires there?). And before all these, about 2 months ago, when my car was cold when I was driving and I pressed the clutch the rpms would drop like crazy and sometimes it would turn off, and this happened until the car warmed up. But I blamed the clutch switch in front of the pedal that was faulty, could that be the start of the O2 failure;

I'm sorry for the long paragraph, but I can't seem to figure out the problem and it's driving me crazy and neither a mechanic wants to spend time to search the cause.

Some info about the 02 sensor:

When it's on idle the voltage that it reads is 0.020 volts and sometimes it jumps to normal volts, when the car is turned off it reads ~1.5 volts. The heater S1 was turning off and on rapidly on idle. And when I tried to test the sensor it said test off and after a while it that it failed, without giving me the option to test it myself manually

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Edited 11 hours ago11 hr by NikoX14

Both of those codes point at the same part. In VCDS terms P1103 is 17511, "Oxygen (Lambda) Sensor Heating; B1 S1: Performance too Low", and Ross-Tech's fix for it is to check the heater of the oxygen sensor before the cat. P0130 is 16514, "Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit", and the cause Ross-Tech list for that one is the same thing, the Bank 1 Sensor 1 heater.

The sensor has to be hot to give a proper signal, so a heater that isn't working would fit what you're seeing: a reading stuck very low at idle, jumping about, and the heater switching on and off. If the ECU believes the mixture is lean it will add fuel, so it could be part of the high idle consumption too.

What I'd check, in this order:

1. The plug for the front (pre-cat) sensor. Unplug it and look for green or burnt pins and a cracked housing, and check the wiring along the exhaust for melted insulation.

2. The heater itself. With the plug off, measure resistance across the heater pins on the sensor side (check a wiring diagram for your engine code, as pinouts vary). No reading at all means the heater is open circuit and the sensor needs replacing.

3. The heater supply on the loom side, including its fuse.

4. Your amp wire. As it all started around the time you ran the cable through the grommet, have a look there for anything nicked, but I'd still start at the sensor plug.

If the heater is open, a new sensor is the fix. Clear the codes afterwards and see whether the idle and the cold stumble settle before you chase anything else.