AutoCodes – BMW – P2042 BMW

P2042 BMW Code - Reductant Temperature Sensor Circuit

Quick Answer

Some manufacturers are now using a diesel exhaust fluid (DEF) system commonly called a selective catalytic reduction (SCR) system to reduce harmful oxides of nitrogen (NOx). Common causes include Faulty Reductant Temperature Sensor, Reductant Temperature Sensor harness is open or shorted, Reductant Temperature Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P2042 BMW indicates Reductant Temperature Sensor Circuit.
Common causes: Common causes include Faulty Reductant Temperature Sensor, Reductant Temperature Sensor harness is open or shorted, Reductant Temperature Sensor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 1,381

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 02, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P2042 BMW Description

Some manufacturers are now using a diesel exhaust fluid (DEF) system commonly called a selective catalytic reduction (SCR) system to reduce harmful oxides of nitrogen (NOx). The diesel exhaust fluid is a Urea based solution of approximately 32% Urea and 64% distilled water. The solution is injected into the exhaust gas stream upstream of the SCR catalyst. Once in the exhaust system it decomposes and becomes Ammonia (NH3) and Carbon dioxide (CO2). Within the catalyst, the NH3 and CO2 react with the Nox to create Oxygen (O2) and harmless Nitrogen (N2).
The system requires a storage tank for the diesel exhaust fluid, a pump with an integrated level sensor, pressure sensor, and fluid quality sensor, an injector fitted to the exhaust system, a fluid heater, and the catalyst.
The system is closely monitored for correct operation as a failure of the system will have a significant impact on vehicle exhaust gas emissions of oxides of Nitrogen.

OBDII Code P2042 BMW - Reductant Temperature Sensor Circuit - AutoCodes.com — P2042 BMW Code - Reductant Temperature Sensor Circuit

What does this mean?

What are the Possible Causes of the DTC P2042 BMW?

Faulty Reductant Temperature Sensor
Reductant Temperature Sensor harness is open or shorted
Reductant Temperature Sensor circuit poor electrical connection

How to Fix the DTC P2042 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P2042 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 P2042 BMW Code

What does OBDII code P2042 mean for a BMW?

OBDII code P2042 indicates a problem with the reductant temperature sensor circuit, which monitors the temperature of the diesel exhaust fluid (DEF) in diesel engines.

What are the common symptoms associated with code P2042?

Common symptoms include reduced engine power, an illuminated check engine light, and potential issues with the diesel exhaust fluid injection system.

What causes the P2042 code to trigger?

The P2042 code can be caused by a faulty reductant temperature sensor, damaged wiring or connectors in the sensor circuit, or issues with the engine control module (ECM).

How can I diagnose the P2042 code?

To diagnose P2042, use an OBDII scanner to confirm the code, inspect the reductant temperature sensor and wiring for damage, and test the sensor's resistance and voltage output.

What are some common repairs for code P2042?

Common repairs include replacing a faulty reductant temperature sensor, repairing damaged wiring or connectors, and reprogramming or replacing the ECM if necessary.

Can I drive my BMW with a P2042 code?

While you can drive with a P2042 code, it may lead to decreased engine performance and could potentially cause further damage to the exhaust system, so itâ€™s advisable to address it promptly.

How much does it typically cost to fix code P2042?

Repair costs for code P2042 can vary widely, typically ranging from $100 to $500, depending on whether the issue is a simple wiring fix or a more complex sensor replacement.

Is there a way to reset the P2042 code after repairs?

Yes, after repairs are made, you can reset the P2042 code using an OBDII scanner or by disconnecting the vehicle battery for a short period.

Will ignoring the P2042 code cause further damage?

Yes, ignoring the P2042 code can lead to more serious issues, including damage to the exhaust system and increased emissions, as well as potential problems with engine performance.