P2201 OBD-II Trouble Code: NOx Sensor Circuit Range/Performance Bank 1

P2201 code definition

NOx Sensor Circuit Range/Performance Bank 1

Related Trouble Codes:

• P2200: NOx Sensor Circuit Bank 1
• P2202: NOx Sensor Circuit Low Input Bank 1
• P2203: NOx Sensor Circuit High Input Bank 1
• P2204: NOx Sensor Circuit Interm Input Bank 1

What the P2201 code means

The P2201 diagnostic trouble code indicates that the nitrogen oxide (NOx) sensor circuit is out of range or has a performance issue.

The purpose of the NOx sensor is to measure the amount of nitric oxide and nitrogen oxide in the exhaust system, and when the storage capacity of these harmful gases has been reached. When the NOx sensor indicates that the storage capacity has been reached, the regeneration phase is initiated by the fueling management system.

Vehicle manufacturers predetermine the appropriate levels of NOx gases that should be present in the fuel management system. The NOx sensor monitors these levels. When the Engine Control Module (ECM) receives information from the NOx sensor that it is out of range/performance, the P2201 diagnostic trouble code will be stored, and the Check Engine Light will come on indicating that there is a problem that needs to be addressed. It is important to note that several drive cycles may be necessary before the Check Engine Light will come on.

What causes the P2201 code?

• NOx sensor wires that are broken or shorted
• NOx sensor connector that is corroded or broken
• NOx sensor connector pins that are bent
• Faulty NOx sensor.
• Engine Control Module that needs to be reprogrammed or replaced

What are the symptoms of the P2201 code?

• The Check Engine Light will come on in the dashboard
• There may be no visible symptoms
• The car may expel more pollutants that it normally should.

How does a mechanic diagnose the P2201 code?

• Uses an OBD-II scanner to retrieve all of the trouble codes that have been stored by the ECM

• Checks with your local dealer for any TSB’s related to this code (a lot of manufacturers have a technical service bulletin (TSB) for this trouble code; it consists of reprogramming the ECM or updating the ECM to get rid of the code)

• Inspects the wiring going to the NOx sensor for shorts or opens in the wiring harness (damaged wiring should be repaired or replaced)

• Inspects the connector to the NOx sensor for corrosion, damage, or bent pins

If the wiring and connector are in good condition:

• Checks to see if the NOx sensor is receiving power - there should be a 12-volt signal going to the sensor (if the NOx sensor is not receiving power, this is an indication the it should be replaced)

Common mistakes when diagnosing the P2201 code

• Failing to inspect the wiring and connector for damage before replacing the NOx sensor

• Failing to check if this code is under a TSB and allowing the dealer to make repairs if the P2201 trouble code is under warranty

How serious is the P2201 code?

The P2201 trouble code does not cause driveability problems. However, operating a vehicle while this trouble code is stored in the ECM will allow harmful gases to be emitted into the environment, and damage to other components of the engine is possible. It is important to have this trouble code diagnosed and repaired without allowing an extended period of time to pass.

What repairs can fix the P2201 code?

• Repairing or replacing damaged NOx sensor wiring
• Repairing or replacing damaged NOx sensor connector
• Replacing NOx sensor
• Reprogramming or replacing the Engine Control Module

Additional comments for consideration regarding the P2201 code

It is often necessary to have this issue repaired by the dealer or by reprogramming the ECM. It is important to first check to see if the repair for this trouble code is covered by warranty before replacing any parts. Keep in mind that it is possible for this issue to be resolved by simply updating the ECM.

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