AutoCodes – BMW – P0140 BMW

P0140 BMW Code - O2 Sensor Circuit Low Voltage Bank 1 Sensor 2

Quick Answer

The heated oxygen sensor 2 (HO2S), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0140 BMW indicates O2 Sensor Circuit Low Voltage Bank 1 Sensor 2.
Common causes: Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 26,278

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Apr 12, 2019

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0140 BMW Description

The heated oxygen sensor 2 (HO2S), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. For optimum catalyst operation, the air fuel mixture (air-fuel ratio) must be maintained near the ideal stoichiometric ratio. The HO2S output voltage changes suddenly in the vicinity of the stoichiometric ratio. The Engine Control Module (ECM) adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The HO2S generates a voltage between 0.1 and 0.9 V in response to oxygen in the exhaust gas. If the oxygen in the exhaust gas increases, the air-fuel ratio becomes Lean. The ECM interprets Lean when the HO2S voltage is below 0.45 V. If the oxygen in the exhaust gas decreases, the air-fuel ratio becomes Rich. The ECM interprets Rich when the HO2S voltage is above 0.45 V.

OBDII Code P0140 BMW - O2 Sensor Circuit Low Voltage Bank 1 Sensor 2 - AutoCodes.com — P0140 BMW Code - O2 Sensor Circuit Low Voltage Bank 1 Sensor 2

What does this mean?

What are the Possible Causes of the DTC P0140 BMW?

Faulty Rear Heated Oxygen Sensor Bank 1
Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
Inappropriate fuel pressure
Faulty fuel injectors
Intake air leaks may be faulty
Exhaust gas leaks

How to Fix the DTC P0140 BMW?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

Replacing the Rear Heated Oxygen Sensor Bank 1 usually takes care of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0140 BMW code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0140 BMW Code

1. What are the common symptoms of OBDII code P0140 in a BMW?

- Common symptoms include poor fuel economy, rough idling, hesitation during acceleration, and the illumination of the check engine light.

2. What does the OBDII code P0140 (O2 Sensor Circuit Low Voltage Bank 1 Sensor 2) in a BMW indicate?

- This code indicates that the oxygen sensor located downstream of the catalytic converter on bank 1 is sending a low voltage signal to the engine control module.

3. What are the possible causes of OBDII code P0140 in a BMW?

- The most common causes include a faulty oxygen sensor, wiring issues in the O2 sensor circuit, exhaust leaks, or a malfunctioning engine control module.

4. How can I diagnose the O2 sensor circuit low voltage issue in my BMW?

- The diagnosis typically involves inspecting the wiring and connections related to the Bank 1 Sensor 2 oxygen sensor, testing the sensor's voltage output, and checking for any exhaust leaks.

5. Can driving with the OBDII code P0140 in a BMW cause further damage?

- While driving with this code may not immediately harm your vehicle, it can lead to decreased fuel efficiency and potentially cause damage to the catalytic converter over time.

6. How can I repair OBDII code P0140 in my BMW?

- Repair options may include replacing the Bank 1 Sensor 2 oxygen sensor, repairing any damaged wiring, fixing exhaust leaks, or reprogramming the engine control module.

7. Is it safe to drive my BMW with the check engine light on due to code P0140?

- It is generally safe to drive with this code, but it is recommended to address the issue promptly to prevent further complications and ensure optimal engine performance.

8. Can I reset the check engine light after fixing the OBDII code P0140 in my BMW?

- Yes, the check engine light can be reset using an OBDII scanner or by disconnecting the car battery for a few minutes. If the issue is resolved, the light should stay off.

9. How much does it typically cost to repair OBDII code P0140 in a BMW?

- The cost of repairs can vary depending on the cause of the issue, but it may range from $100 to $300 for parts and labor, excluding any potential diagnostics fees.

10. How often should the O2 sensors be inspected in a BMW to prevent OBDII code P0140?

- It is recommended to inspect and potentially replace O2 sensors every 60,000 to 90,000 miles to maintain optimal engine performance and avoid triggering codes like P0140.