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P2202 OBD-II Trouble Code: Nitrogen Oxide Sensor (NOx) Sensor Circuit Low Input Bank 1

Check Engine Light

P2202 code definition

Nitrogen Oxide Sensor (NOx) Sensor Circuit Low Input Bank 1

What the P2202 code means

P2202 is an OBD-II generic code for the engine control module (ECM) on a diesel engine vehicle with a NOx sensor detecting the sensor signal is low on bank 1.

What causes the P2202 code?

  • The engine control module (ECM) monitors the NOx sensor bank 1 signal wire and the output voltage, and the ECM is expecting lower than specified voltage for the conditions. When the ECM sees a return voltage below the volts expected, it turns on the Check Engine Light and the code P2202 is set.

  • The NOx sensor is shorted internally or the wiring is shorted causing the low voltage.

  • The NOx sensor is contaminated or clogged with soot.

What are the symptoms of the P2202 code?

  • The Check Engine Light will be illuminated and the code is set in the ECM memory as a fault.

  • The ECM will reduce fuel advance to the injectors to lower the chances of NOx forming in the combustion chamber.

  • The engine may run rich and blow black smoke.

  • The fuel mileage may be more than before failure.

How does a mechanic diagnose the P2202 code?

  • Scans for codes and documents any codes in the ECM, then looks at the freeze frame data for failure

  • Monitors the NOx sensor for bank 1 to see if the signal is shorted at zero volts or if is giving partial readings

  • Removes and replaces the reductant fluid with fresh fluid and runs a regeneration to clean out any soot in the exhaust and NOx sensor

  • Follows the manufacturer pinpoint tests for the diagnosis and replaces the NOx sensor if the regeneration does not cause the NOx sensor to work normal again

Common mistakes when diagnosing the P2202 code

  • Clearing ECM memory codes before checking the freeze frame data for the main failure problem, so the failure may be duplicated and repaired.

  • Not cleaning out the reductant tank and filling it with fresh fluid to run a regeneration action.

How serious is the P2202 code?

  • Code P2202 is a code indicating the engine NOx sensor on bank 1 is not working and the engine will have reduced power to make sure the engine is not putting out NOx. It will do this by running rich to lower combustion chamber temperatures.

What repairs can fix the P2202 code?

  • Clean out the reductant tank and refilling with fresh fluid to run the regeneration cleaning of the exhaust

  • Replacing the NOx sensor for bank one if cleaning did not clean it out

  • Replacing the NOx module if directed by the manufacture pinpoint testing

Additional comments for consideration regarding the P2202 code

Code P2202 is for a bank 1 NOx sensor putting out too low of a voltage. The low voltage may be due to a large buildup of soot on the sensor from the engine not running its regeneration and cleaning out the exhaust of soot buildup. This can be due to the reductant fluid not being refilled, contaminated fluid, or the system having an issue and cannot run the cleaning. If the system has a problem, then this light will be on and a fault code will be present which should be fixed before addressing the NOx code P2202.

Need help with a P2202 code?

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