P2203 — NOx Sensor Circuit High Bank 1
What it means: NOx Sensor Circuit High Bank 1.
How serious / can you keep driving: Serious. Power derate likely — plan to stop soon.
Check first: Check for open in signal wire
Don't risk it — look up listed providers near you and give them this code when you call.
Listed providers nearest Albuquerque, NM
Closest first. Tell them P2203 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Albuquerque, NM · (505) 226-2125
- 0.0 mi away — based in Albuquerque, NM · (505) 823-9696
- 0.0 mi away — based in Albuquerque, NM · (505) 220-3541
Seen on: Heavy Truck/Diesel
What P2203 means
NOx Sensor Circuit High Bank 1. Common causes: NOx sensor signal high.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- NOx sensor signal high
- Open circuit
- failed sensor
First moves (roadside)
- Check for open in signal wire
- replace sensor
FAQ
NOx Sensor Circuit High Bank 1. Common causes: NOx sensor signal high.
Serious — Power derate likely — plan to stop soon.
The most common cause is: NOx sensor signal high. Other possibilities include Open circuit; failed sensor.
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside P2203, or share the same subsystem.
- SCR Operator Inducement — Severe Derate Active (SPN 5246 FMI 0)
- Aftertreatment 1 Diesel Particulate Filter Differential Pressure - Data Valid But Above Normal Operating Range, Most Severe Level (DPF severely restricted / plugged) (SPN 3251 FMI 0)
- Aftertreatment 1 Diesel Exhaust Fluid Quality - Data Valid But Below Normal Operating Range, Most Severe Level (DEF quality/concentration incorrect) (SPN 4364 FMI 1)
- DPF Differential Pressure — Data Erratic (SPN 3251 FMI 2)
- DEF Dosing Unit — Not Responding Properly (SPN 3361 FMI 7)
- SCR Conversion Efficiency — Below Threshold (SPN 4364 FMI 18)
- DEF Quality — Out of Spec (SPN 4094 FMI 31)
- EGR Temperature — Too High (SPN 412 FMI 0)
Same symptom: DEF / SCR fault
Other codes in the DEF and SCR chain — the ones that end in an inducement countdown.
- Reductant System Performance Bank 1 (P204F) · Aftertreatment & Emissions
- Reductant Quality Deviation (P20EA) · Aftertreatment & Emissions
- DEF tank level low (SPN 1761 FMI 18) · Aftertreatment & Emissions
- DEF tank temp sensor — voltage high (SPN 3031 FMI 3) · Aftertreatment & Emissions
- Upstream NOx sensor — internal failure reported (SPN 3216 FMI 12) · Aftertreatment & Emissions
- SCR inlet NOx sensor — erratic (SPN 3216 FMI 2) · Aftertreatment & Emissions
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.