NOx Sensor
Measures oxides of nitrogen in the exhaust, usually in pairs either side of a NOx adsorber or SCR catalyst so the module can judge how much is being converted. That pairing is the thing to understand about its faults: the sensors do not merely report a number, they are the evidence on which an expensive aftertreatment device is condemned. A sensor reading incorrectly convicts a trap or catalyst that is working perfectly, which is why verifying them comes before replacing anything downstream. They also run hot and are slow to reach operating temperature, so faults reported only on short journeys may be a sensor that never warmed up rather than one that has failed.
Also known as: nox probe, nitrogen oxide sensor, scr sensor, nox sender, downstream nox sensor
Referenced by 118 codes
Codes involving this component (118)
- P241D SCR Inducement - Forced Engine Shutdown Stop driving Critical
- P2000 NOx Adsorber Efficiency Below Threshold — Bank 1 High
- P2001 NOx Adsorber Efficiency Below Threshold — Bank 2 High
- P20EE SCR NOx Catalyst Efficiency Below Threshold Bank 1 Catalyst 1 High
- P2200 NOx Sensor Circuit Bank 1 Sensor 1 High
- P2201 NOx Sensor Circuit Range/Performance Bank 1 Sensor 1 High
- P2202 NOx Sensor Circuit Low Bank 1 Sensor 1 High
- P2203 NOx Sensor Circuit High Bank 1 Sensor 1 High
- P2204 NOx Sensor Circuit Intermittent Bank 1 Sensor 1 High
- P2205 NOx Sensor Heater Control Circuit/Open Bank 1 Sensor 1 High
- P2206 NOx Sensor Heater Control Circuit Low Bank 1 Sensor 1 High
- P2207 NOx Sensor Heater Control Circuit High Bank 1 Sensor 1 High
- P2213 NOx Sensor Circuit Bank 2 High
- P2214 NOx Sensor Circuit Range/Performance Bank 2 High
- P2215 NOx Sensor Circuit Low Input Bank 2 High
- P2216 NOx Sensor Circuit High Input Bank 2 High
- P2217 NOx Sensor Circuit Intermittent Input Bank 2 High
- P2218 NOx Sensor Heater Control Circuit/Open Bank 2 High
- P2219 NOx Sensor Heater Control Circuit Low Bank 2 High
- P2220 NOx Sensor Heater Control Circuit High Bank 2 High
- P225D NOx Sensor Performance - Signal Biased/Stuck Low Bank 1 Sensor 1 High
- P24FE SCR Catalyst Incorrect High
- P2BA7 NOx Exceedence - Empty Reagent Tank High
- P2BA8 NOx Exceedence - Interruption of Reagent Dosing Activity High
- P2BA9 NOx Exceedence - Insufficient Reagent Quality High
Other components in Exhaust and Emissions
- Oxygen Sensor 326
- EGR Valve 150
- Catalytic Converter 142
- Reductant Injector 107
- Exhaust Gas Temperature Sensor 95
- Reductant Tank 95
- Diesel Particulate Filter 76
- SCR Catalyst 65
- EGR Cooler 62
- Exhaust Gas Differential Pressure Sensor 58
- Fuel Tank Pressure Sensor 58
- Exhaust Pressure Control Valve 56
- Reductant Heater 55
- Reductant Pump 51
- EVAP Vent Valve 43
- Exhaust Aftertreatment Fuel Injector 42
- Charcoal Canister 33
- EGR Position Sensor 32
- Secondary Air Injection Pump 32
- Reductant Temperature Sensor 29
- EVAP Leak Detection Pump 29
- EVAP Purge Valve 27
- Particulate Matter Sensor 24
- Reductant Control Module 24
- Reductant Level Sensor 23
- Secondary Air Switching Valve 22
- EGR Temperature Sensor 21
- Secondary Air Check Valve 21
- Catalyst Heater 20
- Catalyst Temperature Sensor 20
- Fuel Filler Cap 18
- EGR Cooler Bypass Valve 16
- Reductant Quality Sensor 16
- Exhaust Back Pressure Sensor 15
- Purge Flow Sensor 13
- Direct Ozone Reduction Catalyst 13
- EGR Vacuum Solenoid 9
- Fuel Vapour Temperature Sensor 5
- Fuel Additive Control Module 4
- Fuel Additive Tank 4
Information, not instruction
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