P0137 Code – Oxygen Sensor Low Voltage (Bank 1, Sensor 2)
Table of Contents
What is P0137 Code?
The P0137 code indicates a low voltage condition in the oxygen sensor (O2 sensor) circuit for Bank 1, Sensor 2. This sensor, located downstream of the catalytic converter, monitors exhaust gases to ensure proper emissions and fuel efficiency. If the voltage is consistently low, your car’s ECU triggers the P0137 fault.
Common Symptoms
- Check Engine Light (CEL) illuminated
- Increased fuel consumption
- Rough idle or hesitation under load
- Failed emissions test
- Loss of engine power
Real Owner Example
A Vauxhall Astra owner reported a louder exhaust note and a persistent CEL. Diagnosis revealed a small exhaust leak before Sensor 2, which misled the O2 sensor into low readings. After fixing the leak and resetting the code with the iCarsoft CR MAX, the problem was solved without replacing the sensor.
Possible Causes
- Faulty downstream O2 sensor
- Damaged wiring or loose connector
- Exhaust leak before the catalytic converter
- Clogged or failing catalytic converter
- PCM (Powertrain Control Module) malfunction
Diagnosis Steps
- Scan all trouble codes using iCarsoft CR MAX.
- Inspect exhaust for leaks or holes before Sensor 2.
- Check sensor wiring and connections for corrosion.
- Test O2 sensor voltage response while engine runs.
- Verify catalytic converter efficiency.
Tip: Avoid cheap aftermarket O2 sensors. Genuine or OEM-quality sensors paired with professional diagnostics save time and money long-term.
Repair Solutions
- Replace faulty oxygen sensor
- Repair or replace damaged wiring/connectors
- Seal or weld exhaust leaks
- Replace catalytic converter if clogged
- Reprogram/update PCM software if required
Prevention Tips
- Schedule regular exhaust inspections
- Use quality fuel and engine oil
- Scan your car every few months with iCarsoft diagnostic tools
- Fix exhaust leaks immediately
- Address CEL warnings promptly
Frequently Asked Questions (FAQ)
1. Is P0137 code serious?
Yes. While it may not cause immediate breakdown, prolonged driving with P0137 can damage your catalytic converter and worsen fuel economy.
2. Can I still drive with the P0137 code?
Short trips may be possible, but it’s not recommended. Driving too long with this fault risks costly catalytic converter replacement.
3. How much does it cost to fix P0137?
Replacing a downstream O2 sensor costs $150–$300 with labor. If the catalytic converter is involved, repairs can exceed $1,000.
4. How do I clear the P0137 code?
Use an OBD2 scanner like the iCarsoft CR MAX to clear the fault code after repairs. Clearing without fixing root causes will make the code return.
5. How can I solve P0137 myself?
Inspect exhaust leaks, check sensor wiring, and test the O2 sensor response. DIY repairs are possible if you have the right tools and scanner.
6. Does P0137 affect fuel economy?
Yes, faulty O2 readings can cause rich or lean air-fuel mixtures, reducing MPG and increasing emissions.
7. How do I prevent P0137 from coming back?
Maintain exhaust integrity, use OEM-quality sensors, and run periodic scans with tools from iCarsoft-us.com.
8. Is P0137 related to other O2 sensor codes?
Yes, it may appear with P0138 (high voltage) or P0420 (catalyst efficiency). Always diagnose the root cause.
Recommended Diagnostic Tools
- iCarsoft CR MAX – Advanced multi-system scanner
- iCarsoft CR Eagle – Professional-grade OBD2 diagnostic tool
Why Choose iCarsoft?
- Wide vehicle coverage
- Accurate real-time diagnostics
- User-friendly interface
- Regular free updates
- Trusted by DIYers and professionals
Related Articles：
Vauxhall P0137: HO2S Circuit Low Voltage (Sensor 2) – Location & Fix
P0138: O2 Sensor Circuit High Voltage - Bank 1, Sensor 2
