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P0137 on Ford Mustang

O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)

Factory diagnostic protocol and troubleshooting wire for fault code P0137 specifically for the Ford Mustang (2020–2026, 5.0L Gen 4 Coyote V8 (480HP–500HP Dark Horse) / 2.3L High Output EcoBoost).

Verified OEM Telemetry & Field Repair Tree
Ford Mustang2020–2026
Ford Mustang
Coupe5.0L Gen 4 Coyote V8 (480HP–500HP Dark Horse) / 2.3L High Output EcoBoost
Reliability
Sensor Voltage Ref
0.1V – 5.0V Ref
Mustang SAE Mode $01
ECU Network Bus
500 kbps CAN-FD
ISO 15765-4 Compliant
Drivability Status
Drivable (Short Trip)
Low urgency level
Est. Repair Cost
$100 - $300 (DIY: $35 - $100)
Parts & Labor DIY
Check P0137 On Another Ford Model:
Diagnose P0137 on Specific Mustang Model Year:

1. Symptoms of P0137 on Ford Mustang

When the Engine Control Module (ECM/PCM) on your Ford Mustang (5.0L Gen 4 Coyote V8 (480HP–500HP Dark Horse) / 2.3L High Output EcoBoost) logs fault code P0137, drivers commonly observe:

Check Engine Light on on Ford Mustang (5.0L Gen 4 Coyote V8 (480HP–500HP Dark Horse) / 2.3L High Output EcoBoost)
Downstream sensor voltage consistently below 0.15V on scan tool on Ford Mustang (5.0L Gen 4 Coyote V8 (480HP–500HP Dark Horse) / 2.3L High Output EcoBoost)
Failed emissions test on Ford Mustang (5.0L Gen 4 Coyote V8 (480HP–500HP Dark Horse) / 2.3L High Output EcoBoost)
Ford Mustang OBD-II Port Location
The 16-pin diagnostic connector is located Driver lower dash near OBD trim slot. Plug in your scan tool to verify freeze-frame sensor values.

2. Most Likely Causes on Ford Mustang

Historical warranty claims and technical repair bulletins for Ford Mustang point to the following failure distribution:

55%
Exhaust leak upstream of or directly at the Sensor 2 bung letting in fresh air (Ford OEM Part)
25%
Faulty downstream oxygen sensor (Ford OEM Part)
12%
Short to ground in sensor signal wire (Ford OEM Part)
8%
Extremely lean exhaust condition (Ford OEM Part)
* Source: Synthesized from NHTSA ODI field repair telemetry and verified OEM Technical Service Bulletin (TSB) repair tree frequency percentiles for Ford Mustang.

3. Step-by-Step DIY Repair Guide for Ford Mustang

01
Inspect Exhaust System for Leaks

Listen for exhaust ticking or black soot around flex pipe, flanges, and sensor bungs before the catalytic converter. on the Ford Mustang equipped with 5.0L Gen 4 Coyote V8 (480HP–500HP Dark Horse) / 2.3L High Output EcoBoost.

Required Tool: Flashlight, Jack Stands
02
Check Sensor Signal Voltage with Scan Tool

Monitor B1S2 voltage. Snap the throttle to enrich mixture; voltage should briefly spike above 0.8V. If it remains 0.0V–0.1V, sensor is defective or shorted. on the Ford Mustang equipped with 5.0L Gen 4 Coyote V8 (480HP–500HP Dark Horse) / 2.3L High Output EcoBoost.

Required Tool: OBD-II Scanner
03
Replace Downstream O2 Sensor

Unplug harness, remove old sensor with 7/8 socket, install replacement sensor and plug firmly. on the Ford Mustang equipped with 5.0L Gen 4 Coyote V8 (480HP–500HP Dark Horse) / 2.3L High Output EcoBoost.

Required Tool: O2 Sensor Socket, Ratchet
04
Clear Codes

Clear DTCs and verify B1S2 holds steady between 0.45V and 0.75V during steady highway cruising. on the Ford Mustang equipped with 5.0L Gen 4 Coyote V8 (480HP–500HP Dark Horse) / 2.3L High Output EcoBoost.

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

Equipment for Diagnosing Ford Mustang (P0137)

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Direct-Fit Replacement Part

Ford Mustang OEM Replacement Sensor

4.7 / 5.0 (Verified Fit)

Direct-fit replacement assembly engineered to OEM tolerances for Ford Mustang.

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Sensor Signal Voltage Meter

AstroAI Auto-Ranging Digital Multimeter

4.6 / 5.0 (Best Seller)

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

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Top Mobile OBD-II Scanner

BlueDriver Bluetooth Pro OBDII Scan Tool

4.7 / 5.0 (50,000+ Reviews)

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

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Other Common Fault Codes on Ford Mustang

Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the Ford Mustang:

4. Ford Mustang P0137 FAQs

What causes code P0137 to trigger on a Ford Mustang?

On the Ford Mustang (5.0L Gen 4 Coyote V8 (480HP–500HP Dark Horse) / 2.3L High Output EcoBoost), P0137 is most frequently caused by Exhaust leak upstream of or directly at the Sensor 2 bung letting in fresh air or Faulty downstream oxygen sensor.

Where is the OBD-II port located on my Ford Mustang?

On the Ford Mustang, the 16-pin DLC diagnostic connector is located Driver lower dash near OBD trim slot. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.

Can I safely drive my Ford Mustang with code P0137?

Yes. Vehicle is fully drivable, but Check Engine Light will remain illuminated. Given that P0137 carries a Low severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.