P0471
Exhaust pressure sensor reading not making sense
Severity: MonitorDiesel emissions and glow plugs codes
Modern diesels clean their exhaust with a particulate filter (DPF) that traps soot and burns it off, and a selective catalytic reduction (SCR) system that sprays diesel exhaust fluid (DEF) to cut nitrogen oxides. Sensors for exhaust temperature, filter pressure and NOx keep watch, and glow plugs help cold starting. Many of these faults can lead to a power-limiting derate if they are not fixed.
How these codes differ
- Particulate filter codes split into efficiency, soot load and sensor faults. P2002 means the filter is not trapping soot as well as it should (often a cracked or damaged filter); P2463 means soot has built up too far, usually because regeneration could not finish (frequent short trips, or a sensor or injector fault stopping it); the P2452 to P2455 group is the pressure sensor the computer uses to judge soot load.
- SCR and DEF codes cover NOx conversion (P20EE, efficiency below threshold), DEF level, quality, heater and dosing faults (P203F, reductant level too low, and nearby codes), and the NOx sensors that check the result (P2200 group). EPA notes that running out of DEF, poor DEF quality and sensor faults can all lead to derates, so these are worth fixing promptly.
- Glow plug codes (P0380 group for the glow plug or heater circuit, P0670 for the glow plug control module, P0671 to P0678 for individual cylinders) concern cold-start aids. Rules require the computer to check that the glow plugs respond and, on newer vehicles, to identify which plug failed.
- Exhaust temperature sensor codes (the P0544 group and its relatives) affect regeneration control, so they can lead on to particulate filter codes if left alone.
Diesel emissions and glow plugs codes
P20BA
Diesel exhaust fluid heater not performing as expected
Severity: Severity not verifiedP20EE
Diesel NOx catalyst not removing enough NOx
Severity: Inspect soonP2002
Diesel particulate filter not trapping soot well enough (bank 1)
Severity: MonitorP20B9
Diesel exhaust fluid heater circuit open
Severity: Inspect soonP2459
Diesel particulate filter cleaning cycles happen too often
Severity: MonitorP203B
DEF level sensor reading not plausible
Severity: Inspect soonP2609
Diesel intake air heater system performance fault
Severity: Inspect soonP205C
Diesel exhaust fluid tank temperature sensor reading too low (circuit low)
Severity: Severity not verifiedP207F
Diesel exhaust fluid quality or dosing performance is below what the computer expects
Severity: Inspect soonP2C7A
Diesel NOx catalyst (SCR) efficiency below threshold on bank 1, catalyst 2
Severity: Severity not verifiedP0380
The computer found a fault in glow plug circuit A on a diesel engine
Severity: Severity not verifiedP0381
The computer found a fault in the glow plug warning lamp circuit on a diesel engine
Severity: Severity not verifiedP0472
Exhaust pressure sensor signal reading too low
Severity: Severity not verifiedP0473
Exhaust pressure sensor signal reading too high
Severity: Severity not verifiedP0474
Exhaust pressure sensor signal dropping in and out
Severity: Severity not verifiedP203F
Diesel exhaust fluid level in the tank is too low
Severity: Severity not verifiedP205B
Diesel exhaust fluid tank temperature sensor signal out of range or not plausible
Severity: Severity not verifiedP20C1
The engine computer found an open circuit in the third (C) heater control circuit for the diesel exhaust fluid (DEF) system
Severity: Inspect soonP2200
Fault in the circuit of the bank 1 NOx sensor, the sensor that measures nitrogen oxides in the exhaust
Severity: Severity not verifiedP2463
Soot has built up in the diesel particulate filter beyond the limit the computer allows
Severity: Inspect soon
Sources and review
- Final Regulation Order: 13 CCR §1968.2, Malfunction and Diagnostic System Requirements (OBD II), 2004 and subsequent model-year passenger cars, light-duty trucks and medium-duty vehicles (2015 amendments)
- Diesel Exhaust Fluid
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error