P04xx OBD-II Trouble Codes (Emissions)

P04xx OBD-II Trouble Codes (Emissions)

This is a list of P04xx OBD-II Diagnostic Trouble Codes (DTCs). They all start with P04 (eg P0420, P0455, etc.), the first letter P denotes transmission-related codes, the next 04 numbers indicate that these are additional emissions related codes. The codes below are considered generic as they apply to all makes / models of OBD-II vehicles, although the specific diagnostic and repair steps may differ.

We have literally thousands of other codes listed on the site, use the links below to navigate to other code lists. If you can't find what you are looking for, use our search engine or ask a question on the forums.

Quick links to other trouble codes (starting with): P00xx: P01xx: P02xx: P03xx: P04xx: P05xx: P06xx: P07xx: P08xx: P09xx: P0Axx: P0Bxx: P0Cxx: P1 ***: P20xx: P21xx: P22xx: P23xx: P24xx: P25xx: P26xx: P27xx: P28 / P29 / P2A / P2B: P34xx

For all other codes not listed in the links above or below, see our list of major trouble codes.

OBD-II DTCs - P0400-P0499 - Auxiliary Emission Controls

• P0400 Exhaust Gas Recirculation Flow Malfunction
• P0401 Insufficient Exhaust Gas Recirculation Flow Detected
• P0402 Excessive Exhaust Gas Recirculation Flow Detected
• P0403 Exhaust Gas Recirculation Circuit Malfunction
• P0404 Exhaust Gas Recirculation Circuit Out of Range / Performance
• P0405 Low level of the exhaust gas recirculation sensor signal
• P0406 High Exhaust Gas Recirculation Sensor
• P0407 Low Exhaust Gas Recirculation Sensor Circuit B
• P0408 High signal in the exhaust gas recirculation sensor circuit B
• P0409 Exhaust Gas Recirculation Sensor Circuit "A"
• P040A Exhaust Gas Recirculation Temperature Sensor "A"
• P040B Exhaust Gas Recirculation Temperature Sensor "A" Circuit Range / Performance
• P040C A low value of the sensor "A" of the temperature of the recirculation of the exhaust gases
• P040D A high value of the sensor "A" exhaust gas recirculation temperature
• P040E Unstable / unstable EGR temperature sensor circuit "A"
• P040F Exhaust Gas Recirculation Temperature Sensor "A" / "B" Correlation
• P0410 Secondary air injection system malfunction
• P0411 Wrong Secondary Air Injection System Flow Detected
• P0412 Secondary Air Injection Switching Valve Circuit Malfunction
• P0413 Secondary air system changeover valve A Open circuit
• P0414 Short circuit of the secondary air injection system switching valve circuit
• P0415 Malfunction in the secondary air injection system switching valve B circuit
• P0416 Open circuit of the secondary air injection system switching valve B
• P0417 Short circuit in the secondary air injection system switching valve B circuit
• P0418 Malfunction in the relay circuit "A" of the secondary air injection system
• P0419 Malfunction in the relay circuit "B" of the secondary air injection system
• P041A Exhaust Gas Recirculation Temperature Sensor B Circuit
• P041B Exhaust Gas Recirculation Temperature Sensor "B" Circuit Range / Performance
• P041C A low value of the sensor "B" temperature of the exhaust gas recirculation
• P041D A high value of the sensor "B" temperature of the exhaust gas recirculation
• P041E Unstable / unstable EGR temperature sensor circuit "B"
• P041F A low rate of the valve circuit "A" of the secondary air injection system
• P0420 Catalyst System Efficiency Below Threshold (Bank 1)
• P0421 Catalyst Heating Efficiency Below Threshold (Bank 1)
• P0422 Main Catalyst Efficiency Below Threshold (Bank 1)
• P0423 Catalyst Heating Efficiency Below Threshold (Bank 1)
• P0424 Heated Catalyst Temperature Below Threshold (Bank 1)
• P0425 Catalyst temperature sensor (bank 1, sensor 1)
• P0426 Catalyst Temperature Sensor Out of Range / Performance (Bank 1 Sensor 1)
• P0427 Low indicator of the catalyst temperature sensor (bank 1, sensor 1)
• P0428 High signal of the catalyst temperature sensor (bank 1, sensor 1)
• P0429 Catalyst Heater Control Circuit (Bank 1)
• P042A Catalyst Temperature Sensor Circuit (Bank 1, Sensor 2)
• P042B Catalyst Temperature Sensor Circuit Range / Performance (Bank 1 Sensor 2)
• P042C Low indicator circuit of the catalyst temperature sensor (block 1, sensor 2)
• P042D High signal in the catalyst temperature sensor circuit (bank 1, sensor 2)
• P042E Exhaust Gas Recirculation Control "A" Stuck Open
• P042F Exhaust Gas Recirculation Control "A" Stuck Closed
• P0430 Catalyst System Efficiency Below Threshold (Bank 2)
• P0431 Catalyst Heating Efficiency Below Threshold (Bank 2)
• P0432 Main Catalyst Efficiency Below Threshold (Bank 2)
• P0433 Catalyst Heating Efficiency Below Threshold (Bank 2)
• P0434 Heated Catalyst Temperature Below Threshold (Bank 2)
• P0435 Catalyst Temperature Sensor Circuit Malfunction (Bank 2, Sensor 1)
• P0436 Catalyst temperature sensor circuit out of range / performance (bank 2, sensor 1)
• P0437 Low indicator circuit of the catalyst temperature sensor (Bank 2, sensor 1)
• P0438 High signal in the catalyst temperature sensor circuit (bank 2, sensor 1)
• P0439 Catalyst Heater Control Circuit (Bank 2)
• P043A Catalyst Temperature Sensor Circuit (Bank 2, Sensor 2)
• P043B Catalyst Temperature Sensor Circuit Range / Performance (Bank 2 Sensor 2)
• P043C Low indicator circuit of the catalyst temperature sensor (block 2, sensor 2)
• P043D High signal in the catalyst temperature sensor circuit (bank 2, sensor 2)
• P043E Low flow rate of the reference diaphragm of the fuel vapor recovery system
• P043F Evaporative emission system support diaphragm, high flow
• P0440 Malfunction of the control system for the removal of fuel vapor
• P0441 Incorrect purging of the control system for the removal of fuel vapor
• P0442 Evaporative Emission Control System Leak Detected (Small Leak)
• P0443 Evaporative Emission Control System Purge Valve Circuit
• P0444 Open circuit of the purge valve of the fuel vapor control system
• P0445 Short circuit of the purge valve circuit of the fuel vapor control system
• P0446 Malfunction of the control circuit of the ventilation hole of the control system for the removal of fuel vapor
• P0447 Open control circuit of the vent control system for the removal of fuel vapor
• P0448 Short circuit of the control circuit of the vent control system for the removal of fuel vapor
• P0449 Malfunction of the ventilation valve / solenoid circuit of the fuel vapor control system
• P044A Exhaust Gas Recirculation Sensor C Circuit
• P044B Exhaust Gas Recirculation Sensor "C" Circuit Range / Performance
• P044C Low indicator of the sensor "C" of the exhaust gas recirculation system
• P044D A high value of the sensor "C" of the exhaust gas recirculation system
• P044E Intermittent / unstable EGR sensor circuit "C"
• P044F Switching valve "A" secondary air injection system, high signal
• P0450 Malfunction of the pressure sensor of the control system for the removal of fuel vapor
• P0451 The pressure sensor of the control system for the removal of gasoline vapor is out of the performance range
• P0452 Low level of the input signal of the pressure sensor of the control system for the removal of fuel vapor
• P0453 High input of the pressure sensor of the control system for the removal of fuel vapor
• P0454 Intermittent signal of the pressure sensor of the control system for the removal of fuel vapor
• P0455 Evaporative Emission Control System Leak Detected (Coarse Leak)
• P0456 A small leak in the fuel vapor recovery system has been detected
• P0457 Evaporative Emission Control System Leak Detected
• P0458 Low rate of the valve circuit of the purge of the EVAP system
• P0459 A high rate of the valve circuit of the purge of the EVAP system
• P045A Exhaust Gas Recirculation Control Circuit "B"
• P045B Exhaust Gas Recirculation Control Circuit "B" Out of Range / Performance
• P045C Low rate of the exhaust gas recirculation control circuit "B"
• P045D Exhaust Gas Recirculation Control Circuit "B" High
• P045E Exhaust Gas Recirculation Control "B" stuck open
• P045F Exhaust gas recirculation regulator "B" stuck in closed position
• P0460 Fuel Level Sensor Circuit Malfunction
• P0461 Fuel level sensor circuit out of range / performance
• P0462 Low input of the fuel level sensor circuit
• P0463 High signal level in the fuel level sensor circuit
• P0464 Fuel Level Sensor Intermittent Circuit
• P0465 Purge Flow Sensor Circuit Malfunction
• P0466 Purge Sensor Circuit Range / Performance
• P0467 Low input signal of the purge flow sensor circuit
• P0468 High purge flow sensor circuit input
• P0469 Purge Flow Sensor Circuit Malfunction
• P046A Correlation 1/2 catalyst temperature sensor (Bank 1)
• P046B Correlation 1/2 catalyst temperature sensor (Bank 2)
• P046C Exhaust Gas Recirculation Sensor "A" Circuit Range / Performance
• P046D Intermittent / unstable EGR sensor circuit "A"
• P046E Exhaust Gas Recirculation Sensor "B" Circuit Range / Performance
• P046F Intermittent / unstable EGR sensor circuit "B"
• P0470 Exhaust Gas Pressure Sensor A Circuit
• P0471 Exhaust Gas Pressure Sensor "A" Circuit Range / Performance
• P0472 Low sensor "A" exhaust pressure
• P0473 High Exhaust Gas Pressure Sensor "A"
• P0474 Exhaust Gas Pressure Sensor A Circuit Malfunction
• P0475 Exhaust Gas Pressure Regulating Valve "A"
• P0476 Exhaust gas pressure control valve "A" out of range / performance
• P0477 A low value of the exhaust pressure control valve "A"
• P0478 High signal of the exhaust pressure control valve "A"
• P0479 Malfunction of the exhaust pressure control valve "A"
• P047A Exhaust Gas Pressure Sensor B Circuit
• P047B Exhaust Gas Pressure Sensor "B" Circuit Range / Performance
• P047C Low sensor "B" exhaust pressure
• P047D A high indicator of the sensor "B" exhaust pressure
• P047E Intermittent / unstable exhaust gas pressure sensor circuit "B"
• P047F Exhaust gas pressure control valve "A" stuck open
• P0480 Cooling Fan I Control Circuit Malfunction
• P0481 Cooling Fan 2 Control Circuit Malfunction
• P0482 Cooling Fan 3 Control Circuit Malfunction
• P0483 Cooling Fan Rationality Check Malfunction
• P0484 Cooling Fan Circuit Overload
• P0485 Cooling Fan Power / Ground Circuit Malfunction
• P0486 Exhaust Gas Recirculation Sensor Circuit "B"
• P0487 Open circuit of the throttle valve EGR "A"
• P0488 Exhaust Gas Recirculation Throttle Control Circuit "A" Range / Performance
• P0489 Low rate of the exhaust gas recirculation control circuit "A"
• P048A Exhaust gas pressure regulating valve "A" stuck in closed position
• P048B Exhaust Pressure Control Valve Position Sensor / Switch Circuit
• P048C Exhaust Pressure Control Valve Position Sensor / Circuit Switch Range / Performance
• P048D Low Exhaust Pressure Control Valve Position Sensor / Switch Circuit
• P048E High signal in the exhaust pressure control valve position sensor / switch circuit
• P048F Intermittent / Intermittent Exhaust Pressure Control Valve Position Sensor / Switch Circuit
• P0490 Exhaust Gas Recirculation Control Circuit "A" High
• P0491 Insufficient flow of secondary air injection system, bank 1
• P0492 Insufficient flow of secondary air injection system, bank 2
• P0493 Fan Overspeed
• P0494 Low fan speed
• P0495 Fan Speed ​​High
• P0496 EVAP flow in the absence of purge
• P0497 Low purge flow rate of the fuel vapor recovery system
• P0498 Low rate of the control circuit of the ventilation valve of the EVAP system
• P0499 High signal level in the control circuit of the ventilation valve of the EVAP system
• P049A Exhaust Gas Recirculation System "B" Flow
• P049B Insufficient Exhaust Gas Recirculation Flow Detected "B"
• P049C Excessive Exhaust Gas Recirculation Flow Detected "B"
• P049D Exhaust Gas Recirculation Control Position "A" exceeds the learning limit
• P049E Exhaust Gas Recirculation Control Position "B" exceeds the learning limit
• P049F Exhaust gas pressure control valve "B"
• P04A0 Exhaust gas pressure control valve "B" range / performance
• P04A1 Exhaust gas pressure control valve "B" low
• P04A2 Exhaust gas pressure control valve "B" high
• P04A3 Exhaust gas pressure control valve "B" Intermittent
• P04A4 Exhaust gas pressure control valve "B" stuck open
• P04A5 Exhaust gas pressure control valve "B" stuck in closed position
• P04A6 Exhaust Gas Pressure Control Valve Position Sensor / Switch "B"
• P04A7 Exhaust Gas Pressure Control Valve "B" Position Sensor / Range / Performance Switch
• P04A8 Exhaust Gas Pressure Control Valve Position / Switch Position Sensor "B" Low
• P04A9 High signal in the sensor / switch position of the exhaust pressure control valve "B"
• P04AA Exhaust gas pressure control valve "B" position sensor / switch circuit unstable / unstable
• P04AB – P04FF ISO / SAE Reserved

Next: Trouble Codes P0500-P0599

Quick links to other trouble codes (starting with): P00xx: P01xx: P02xx: P03xx: P04xx: P05xx: P06xx: P07xx: P08xx: P09xx: P0Axx: P0Bxx: P0Cxx: P1 ***: P20xx: P21xx: P22xx: P23xx: P24xx: P25xx: P26xx: P27xx: P28 / P29 / P2A / P2B: P34xx

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