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P0155AudiAudi Q3 HubAll Audi P0155Medium Severity

P0155 on Audi Q3

O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

Factory diagnostic protocol and troubleshooting wire for fault code P0155 specifically for the Audi Q3 (2020–2026, 2.0L TFSI Turbo 4-Cyl (228HP / S-tronic / quattro AWD)).

Verified OEM Telemetry & Field Repair Tree
Audi Q32020–2026
Audi Q3
SUV2.0L TFSI Turbo 4-Cyl (228HP / S-tronic / quattro AWD)
Reliability
Sensor Voltage Ref
0.1V – 5.0V Ref
Q3 SAE Mode $01
ECU Network Bus
500 kbps CAN-FD
ISO 15765-4 Compliant
Drivability Status
Drivable (Short Trip)
Medium urgency level
Est. Repair Cost
$120 - $350 (DIY: $45 - $120)
Parts & Labor DIY
Check P0155 On Another Audi Model:
Diagnose P0155 on Specific Q3 Model Year:

1. Symptoms of P0155 on Audi Q3

When the Engine Control Module (ECM/PCM) on your Audi Q3 (2.0L TFSI Turbo 4-Cyl (228HP / S-tronic / quattro AWD)) logs fault code P0155, drivers commonly observe:

Check Engine Light on immediately after cold start on Audi Q3 (2.0L TFSI Turbo 4-Cyl (228HP / S-tronic / quattro AWD))
Slightly increased cold-start emissions on Audi Q3 (2.0L TFSI Turbo 4-Cyl (228HP / S-tronic / quattro AWD))
No major driving performance issues once engine reaches full operating temperature on Audi Q3 (2.0L TFSI Turbo 4-Cyl (228HP / S-tronic / quattro AWD))
Audi Q3 OBD-II Port Location
The 16-pin diagnostic connector is located Driver side lower knee panel. Plug in your scan tool to verify freeze-frame sensor values.

2. Most Likely Causes on Audi Q3

Historical warranty claims and technical repair bulletins for Audi Q3 point to the following failure distribution:

55%
Burnt-out heating element inside the Bank 2 Sensor 1 O2 sensor (Audi OEM Part)
25%
Blown O2 heater fuse in under-hood fuse block (Audi OEM Part)
12%
Corroded or broken heater power/ground wiring (Audi OEM Part)
8%
Faulty heater driver circuit in the PCM (Audi OEM Part)
* Source: Synthesized from NHTSA ODI field repair telemetry and verified OEM Technical Service Bulletin (TSB) repair tree frequency percentiles for Audi Q3.

3. Step-by-Step DIY Repair Guide for Audi Q3

01
Check O2 Heater Fuse

Inspect the O2 HTR fuse in the engine fuse box with a test light or multimeter. on the Audi Q3 equipped with 2.0L TFSI Turbo 4-Cyl (228HP / S-tronic / quattro AWD).

Required Tool: Fuse Puller, Test Light
02
Test Heater Resistance on Bank 2 Sensor 1

Unplug the sensor connector and measure resistance between the two heater pins. An open circuit (infinite ohms / OL) confirms a dead internal heater. on the Audi Q3 equipped with 2.0L TFSI Turbo 4-Cyl (228HP / S-tronic / quattro AWD).

Required Tool: Digital Multimeter
03
Replace Bank 2 Upstream O2 Sensor

Remove faulty sensor and install a new OEM oxygen sensor with built-in heater. on the Audi Q3 equipped with 2.0L TFSI Turbo 4-Cyl (228HP / S-tronic / quattro AWD).

Required Tool: 22mm O2 Sensor Socket, Ratchet
04
Clear Codes and Perform Cold Start Verification

Clear DTCs and allow engine to cool down, then restart to confirm P0155 does not return. on the Audi Q3 equipped with 2.0L TFSI Turbo 4-Cyl (228HP / S-tronic / quattro AWD).

Required Tool: OBD-II Scanner
Recommended Parts & Testing Tools

Equipment for Diagnosing Audi Q3 (P0155)

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Direct-fit replacement assembly engineered to OEM tolerances for Audi Q3.

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Sensor Signal Voltage Meter

AstroAI Auto-Ranging Digital Multimeter

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Essential for testing 0.1V–5.0V sensor reference signals, ground continuity (<0.20Ω), and harness resistance.

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BlueDriver Bluetooth Pro OBDII Scan Tool

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Reads and clears enhanced codes (ABS, Airbag, Transmission, Engine) & live freeze-frame telemetry on phone.

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Other Common Fault Codes on Audi Q3

Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the Audi Q3:

4. Audi Q3 P0155 FAQs

What causes code P0155 to trigger on a Audi Q3?

On the Audi Q3 (2.0L TFSI Turbo 4-Cyl (228HP / S-tronic / quattro AWD)), P0155 is most frequently caused by Burnt-out heating element inside the Bank 2 Sensor 1 O2 sensor or Blown O2 heater fuse in under-hood fuse block.

Where is the OBD-II port located on my Audi Q3?

On the Audi Q3, the 16-pin DLC diagnostic connector is located Driver side lower knee panel. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.

Can I safely drive my Audi Q3 with code P0155?

Yes. The sensor will take longer to warm up, causing brief open-loop fuel delay on cold starts. Given that P0155 carries a Medium severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.