16515moderate severityPowertrain
O2 Sensor Circuit Low Voltage Bank 1 Sensor 1
on 2004 Volkswagen Touareg 3.2L V6 · AWD
What this code means
The upstream oxygen sensor signal voltage is too low on Bank 1 Sensor 1 (OBD P0131). This indicates a lean signal or circuit fault.
Symptoms
- Poor fuel economy
- Hesitation
- Check engine light on
Common causes
- Faulty oxygen sensor
- Short to ground in wiring
- Exhaust leak
- Lean fuel mixture
Diagnostic steps
- Read live O2 sensor voltage
- Inspect wiring for short to ground
- Check for exhaust and intake leaks
- Test sensor response
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