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P0140 on Acura MDX

O2 Sensor Circuit No Activity (Bank 1 Sensor 2)

Factory diagnostic protocol and troubleshooting wire for fault code P0140 specifically for the Acura MDX (2022–2026, 3.5L i-VTEC V6 (290HP) / 3.0L Turbo V6 (Type S 355HP / SH-AWD)).

Verified OEM Telemetry & Field Repair Tree
Acura MDX2022–2026
Acura MDX
SUV3.5L i-VTEC V6 (290HP) / 3.0L Turbo V6 (Type S 355HP / SH-AWD)
Reliability
Sensor Voltage Ref
0.1V – 5.0V Ref
MDX 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 P0140 On Another Acura Model:
Diagnose P0140 on Specific MDX Model Year:

1. Symptoms of P0140 on Acura MDX

When the Engine Control Module (ECM/PCM) on your Acura MDX (3.5L i-VTEC V6 (290HP) / 3.0L Turbo V6 (Type S 355HP / SH-AWD)) logs fault code P0140, drivers commonly observe:

Check Engine Light on on Acura MDX (3.5L i-VTEC V6 (290HP) / 3.0L Turbo V6 (Type S 355HP / SH-AWD))
Downstream sensor flatlined at static 0.45V bias voltage on Acura MDX (3.5L i-VTEC V6 (290HP) / 3.0L Turbo V6 (Type S 355HP / SH-AWD))
Emissions readiness monitor incomplete on Acura MDX (3.5L i-VTEC V6 (290HP) / 3.0L Turbo V6 (Type S 355HP / SH-AWD))
Acura MDX OBD-II Port Location
The 16-pin diagnostic connector is located Driver side lower dash assembly. Plug in your scan tool to verify freeze-frame sensor values.

2. Most Likely Causes on Acura MDX

Historical warranty claims and technical repair bulletins for Acura MDX point to the following failure distribution:

55%
Completely dead downstream O2 sensor (Acura OEM Part)
25%
Disconnected sensor harness plug under car (Acura OEM Part)
12%
Cut or broken signal wire in vehicle harness (Acura OEM Part)
8%
Corroded terminal pins in connector (Acura OEM Part)
* Source: Synthesized from NHTSA ODI field repair telemetry and verified OEM Technical Service Bulletin (TSB) repair tree frequency percentiles for Acura MDX.

3. Step-by-Step DIY Repair Guide for Acura MDX

01
Check Sensor Connection Underbody

Inspect harness connector under vehicle floor pan. Verify plug is firmly seated and weather seal is intact. on the Acura MDX equipped with 3.5L i-VTEC V6 (290HP) / 3.0L Turbo V6 (Type S 355HP / SH-AWD).

Required Tool: Flashlight, Jack Stands
02
Test Sensor Heater & Signal Circuit

Check for 12V heater power and ground at connector with ignition ON. on the Acura MDX equipped with 3.5L i-VTEC V6 (290HP) / 3.0L Turbo V6 (Type S 355HP / SH-AWD).

Required Tool: Multimeter
03
Replace Downstream Oxygen Sensor

Remove and replace the downstream oxygen sensor with an OEM-spec part. on the Acura MDX equipped with 3.5L i-VTEC V6 (290HP) / 3.0L Turbo V6 (Type S 355HP / SH-AWD).

Required Tool: O2 Sensor Socket, Ratchet
04
Clear DTC Codes

Clear code and verify sensor activity returns on live telemetry. on the Acura MDX equipped with 3.5L i-VTEC V6 (290HP) / 3.0L Turbo V6 (Type S 355HP / SH-AWD).

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

Equipment for Diagnosing Acura MDX (P0140)

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Direct-Fit Replacement Part

Acura MDX OEM Replacement Sensor

4.7 / 5.0 (Verified Fit)

Direct-fit replacement assembly engineered to OEM tolerances for Acura MDX.

$45 – $95 Prime
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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.

$29.99 Prime
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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.

Compare OEM & Aftermarket Replacement Sensors for Acura MDXVerified direct-fit pricing from Denso, Bosch, Motorcraft, and ACDelco on Amazon.
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Other Common Fault Codes on Acura MDX

Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the Acura MDX:

4. Acura MDX P0140 FAQs

What causes code P0140 to trigger on a Acura MDX?

On the Acura MDX (3.5L i-VTEC V6 (290HP) / 3.0L Turbo V6 (Type S 355HP / SH-AWD)), P0140 is most frequently caused by Completely dead downstream O2 sensor or Disconnected sensor harness plug under car.

Where is the OBD-II port located on my Acura MDX?

On the Acura MDX, the 16-pin DLC diagnostic connector is located Driver side lower dash assembly. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.

Can I safely drive my Acura MDX with code P0140?

Yes, safe for normal driving without risk of breakdown. Given that P0140 carries a Low severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.