AutoCodes – Generic – U05A1

U05A1 Code - NOx Sensor 'A' Received Invalid Data From ECM/PCM

Quick Answer

The Powertrain Control Module (PCM) monitors the Nitrogen Oxide (NOx) Sensor 'A'. Common causes include Faulty Nitrogen Oxide (NOx) Sensor 'A', Nitrogen Oxide (NOx) Sensor 'A' harness is open or shorted, Nitrogen Oxide (NOx) Sensor 'A' 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: U05A1 indicates NOx Sensor 'A' Received Invalid Data From ECM/PCM.
Common causes: Common causes include Faulty Nitrogen Oxide (NOx) Sensor 'A', Nitrogen Oxide (NOx) Sensor 'A' harness is open or shorted, Nitrogen Oxide (NOx) Sensor 'A' 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 1,363

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 Apr 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U05A1 Description

The Powertrain Control Module (PCM) monitors the Nitrogen Oxide (NOx) Sensor 'A'. The Diagnostic Trouble Code (DTC) sets when an unexpected data link message was sent to the PCM form the Nitrogen Oxide (NOx) Sensor 'A' and was unable to be interpreted.

OBDII Code U05A1 - NOx Sensor 'A' Received Invalid Data From ECM/PCM - AutoCodes.com — U05A1 Code - NOx Sensor 'A' Received Invalid Data From ECM/PCM

What does this mean?

What are the Possible Causes of the DTC U05A1?

Faulty Nitrogen Oxide (NOx) Sensor 'A'
Nitrogen Oxide (NOx) Sensor 'A' harness is open or shorted
Nitrogen Oxide (NOx) Sensor 'A' circuit poor electrical connection

How to Fix the DTC U05A1?

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 U05A1 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.

Need more information about the U05A1 code?

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Information for Specific Makes

U05A1 Ford — NOx Sensor 'A' Received Invalid Data From ECM/PCM
U05A1 Lincoln — NOx Sensor 'A' Received Invalid Data From ECM/PCM
U05A1 Mercury — NOx Sensor 'A' Received Invalid Data From ECM/PCM

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 U05A1 Code

What does the OBDII code U05A1 mean?

The OBDII code U05A1 indicates that the NOx sensor 'A' is receiving invalid data from the Engine Control Module (ECM) or Powertrain Control Module (PCM).

What symptoms might indicate a U05A1 code?

Common symptoms can include illuminated check engine light, reduced engine performance, increased emissions, and in some cases, poor fuel economy.

What could cause the U05A1 code to trigger?

The U05A1 code can be triggered due to faulty wiring or connectors, a malfunctioning NOx sensor, or issues within the ECM/PCM itself.

How can I diagnose the U05A1 code?

To diagnose the U05A1 code, you should start by visually inspecting the NOx sensor and its wiring for any damage. Then, use an OBDII scanner to check for related codes and perform tests on the NOx sensorâ€™s output.

Is it safe to drive with a U05A1 code?

While it may be safe to drive, it is advisable to address the U05A1 code as it can lead to increased emissions and potential damage to the vehicleâ€™s exhaust system or engine performance.

What repairs are commonly needed for a U05A1 code?

Repairs may include replacing the NOx sensor, repairing any damaged wiring or connectors, or reprogramming/updating the ECM if it is found to be faulty.

Can I reset the U05A1 code after repairs?

Yes, after performing the necessary repairs, you can reset the U05A1 code using an OBDII scanner. However, it's best to ensure that the issue is fully resolved before resetting.

Will clearing the code fix the problem?

Clearing the code will not fix the underlying issue. If the problem persists, the code will likely return after driving the vehicle for a short time.

How much does it typically cost to fix a U05A1 code?

Repair costs can vary widely depending on the specific issue but may range from $100 to $600, depending on whether you need to replace a sensor or repair wiring.