P2051 OBD-II Trouble Code: Reductant Injector Circuit Low Bank 1 Unit 1

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Cost of diagnosing the P2051 code

P2051 is a diagnostic trouble code (DTC) for "Reductant Injector Circuit Low Bank 1 Unit 1". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

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P2051 code definition

Reductant injector circuit low bank 1 unit 1

What the P2051 code means

This trouble code indicates that the powertrain control module has noticed a malfunction with the reductant injector air circuit.

What are the causes of the P2051 code?

Some potential causes of this trouble code would include:

  • Damaged wiring connectors that are in the injector air circuit could be damaged.
  • The injector air sensor could be damaged.
  • The powertrain control module could be malfunctioning
  • An exhaust system could have been installed that does not meet the manufacturer’s requirements.
  • A large exhaust leak may exist.

What are the symptoms of the P2051 code?

The symptoms that the driver with this trouble code may experience would be occasional black smoke coming from the tailpipe and the Check Engine Light being illuminated.

How does a mechanic diagnose the P2051 code?

A visual inspection of the exhaust system to check the injector air sensor and its wiring would be a wise place for a mechanic to start. If the issue is not found, the mechanic would then ensure that the vehicle has the correct exhaust system and that no leaks exist.

Once this has been confirmed, if the problem still exists, the powertrain control module would be tested using the manufacturer’s recommended procedure. Any malfunctioning parts that were found during this inspection would be noted and relayed to the customer to make a repair decision.

Common mistakes when diagnosing the P2051 code

A common mistake that could be made during the diagnosis of this issue would be to replace parts without properly testing them. This mistake can apply to any Check Engine Light diagnosis. Most manufacturers offer a diagnostic procedure for all Check Engine Light codes, so it is important to follow these procedures.

How serious is the P2051 code?

Considering that this trouble code does not cause any drivability issues, I would consider this to be low on the seriousness scale. Though, it would be unpleasant to have people behind you getting angry all the time due to the excess emissions from your car. Just like with any Check Engine Light, it is best to resolve the problem as soon as possible.

What repairs can fix the P2051 code?

Repairs that can fix this trouble code would include:

  • Repairing or replacing wiring that is in the exhaust temperature/pressure circuit

  • Replacing the exhaust temperature/pressure sensor

  • Replacing an aftermarket exhaust system with an exhaust system that meets the manufacturer’s specifications

  • Repairing a large exhaust leak upstream of the exhaust temperature/pressure sensor

  • Replacing the powertrain control module

Additional comments regarding the P2051 code

When this trouble code is stored on your vehicle, be sure to run the engine in well ventilated areas as much as possible due to the excess gasses that come out of the tailpipe and pollute the air.

Need help with a P2051 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230

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17 years of experience
Toyota Corolla - Check Engine Light is on - New Braunfels, Texas
As always, punctual and professional. He explains the problem thoroughly. I feel confident in his work and knowledge.

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Lincoln Aviator - Check Engine Light is on - San Antonio, Texas
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Chevrolet Trax - Check Engine Light is on - Grosse Pointe, Michigan
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