P203B on Land Rover
Reductant Level Sensor "A" Circuit Range/Performance
P203B on Land Rover vehicles indicates reductant level sensor "a" circuit range/performance. Au7o has documented this code across 1 Land Rover model — most commonly on Range Rover Velar. P203B indicates the engine control module has detected an implausible or out-of-range signal from the reductant (diesel exhaust fluid / DEF) level sensor "A" in the SCR aftertreatment system. This sensor, typically built into the DEF storage tank, reports how much reductant remains so the vehicle can dose DEF correctly to reduce NOx emissions. A range/performance fault means the reading is present but does not make sense compared to expected values.
Common Causes of P203B
- •Faulty or stuck reductant (DEF) level sensor inside the DEF tank
- •Contaminated, crystallized, or degraded DEF fluid affecting the sensor reading
- •Wiring or connector issues (corrosion, chafing, loose pins) in the level sensor circuit
- •Incorrect DEF fluid level or air pockets/sloshing causing implausible readings
- •Faulty DEF tank header/sender unit
- •ECM/PCM software or calibration fault
P203B on Land Rover by Model
Land Rover Range Rover Velar(1 issue)
- AdBlue/DEF System Faults and Injector Crystallization2018-2024
JLR records for 2018-2020 diesel Velar vehicles document DEF dosing or quality warnings, restart countdowns and DTCs including P203B-31, P208A-13 and P208C-11. One primary record directs technicians to check DEF quality and inspect the injector for crusting or leaks, but treats the condition as under investigation. The evidence does not establish injector, heater and level-sensor failure across 2018-2024.
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View P203B across all makes →Frequently Asked Questions
What does P203B mean on Land Rover?▼
P203B stands for "Reductant Level Sensor "A" Circuit Range/Performance." P203B indicates the engine control module has detected an implausible or out-of-range signal from the reductant (diesel exhaust fluid / DEF) level sensor "A" in the SCR aftertreatment system. This sensor, typically built into the DEF storage tank, reports how much reductant remains so the vehicle can dose DEF correctly to reduce NOx emissions. A range/performance fault means the reading is present but does not make sense compared to expected values. On Land Rover specifically, this code is documented across 1 model.
What causes P203B on Land Rover vehicles?▼
Common causes on Land Rover: Faulty or stuck reductant (DEF) level sensor inside the DEF tank, Contaminated, crystallized, or degraded DEF fluid affecting the sensor reading, Wiring or connector issues (corrosion, chafing, loose pins) in the level sensor circuit, Incorrect DEF fluid level or air pockets/sloshing causing implausible readings, Faulty DEF tank header/sender unit. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P203B on a Land Rover?▼
Repair costs vary widely depending on the root cause and specific Land Rover model.
Which Land Rover models have P203B documented?▼
Au7o has documented P203B on 1 Land Rover model: Range Rover Velar.