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P0155 on Ford Explorer

O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

Factory diagnostic protocol and troubleshooting wire for fault code P0155 specifically for the Ford Explorer (2020–2026, 2.3L EcoBoost 4-Cyl (300HP) / 3.0L Twin-Turbo EcoBoost V6 (ST 400HP)).

Verified OEM Telemetry & Field Repair Tree
Ford Explorer2020–2026
Ford Explorer
SUV2.3L EcoBoost 4-Cyl (300HP) / 3.0L Twin-Turbo EcoBoost V6 (ST 400HP)
Reliability
Sensor Voltage Ref
0.1V – 5.0V Ref
Explorer 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 Ford Model:
Diagnose P0155 on Specific Explorer Model Year:

1. Symptoms of P0155 on Ford Explorer

When the Engine Control Module (ECM/PCM) on your Ford Explorer (2.3L EcoBoost 4-Cyl (300HP) / 3.0L Twin-Turbo EcoBoost V6 (ST 400HP)) logs fault code P0155, drivers commonly observe:

Check Engine Light on immediately after cold start on Ford Explorer (2.3L EcoBoost 4-Cyl (300HP) / 3.0L Twin-Turbo EcoBoost V6 (ST 400HP))
Slightly increased cold-start emissions on Ford Explorer (2.3L EcoBoost 4-Cyl (300HP) / 3.0L Twin-Turbo EcoBoost V6 (ST 400HP))
No major driving performance issues once engine reaches full operating temperature on Ford Explorer (2.3L EcoBoost 4-Cyl (300HP) / 3.0L Twin-Turbo EcoBoost V6 (ST 400HP))
Ford Explorer OBD-II Port Location
The 16-pin diagnostic connector is located Lower steering column dash trim. Plug in your scan tool to verify freeze-frame sensor values.

2. Most Likely Causes on Ford Explorer

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

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

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

01
Check O2 Heater Fuse

Inspect the O2 HTR fuse in the engine fuse box with a test light or multimeter. on the Ford Explorer equipped with 2.3L EcoBoost 4-Cyl (300HP) / 3.0L Twin-Turbo EcoBoost V6 (ST 400HP).

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 Ford Explorer equipped with 2.3L EcoBoost 4-Cyl (300HP) / 3.0L Twin-Turbo EcoBoost V6 (ST 400HP).

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 Ford Explorer equipped with 2.3L EcoBoost 4-Cyl (300HP) / 3.0L Twin-Turbo EcoBoost V6 (ST 400HP).

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 Ford Explorer equipped with 2.3L EcoBoost 4-Cyl (300HP) / 3.0L Twin-Turbo EcoBoost V6 (ST 400HP).

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

Equipment for Diagnosing Ford Explorer (P0155)

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Ford Explorer OEM Replacement Sensor

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

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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

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 Explorer

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

4. Ford Explorer P0155 FAQs

What causes code P0155 to trigger on a Ford Explorer?

On the Ford Explorer (2.3L EcoBoost 4-Cyl (300HP) / 3.0L Twin-Turbo EcoBoost V6 (ST 400HP)), 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 Ford Explorer?

On the Ford Explorer, the 16-pin DLC diagnostic connector is located Lower steering column dash trim. 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 Explorer 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.