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P0400–P0499 fault codes
22 codes in this range have a plain-English write-up, checked by a person.
P0400P0400: the exhaust recirculation system has a flow faultP0401P0401: not enough exhaust is being fed back into the engineP0402P0402: too much exhaust is being fed back into the engineP0403P0403: the exhaust recirculation valve's circuit has a faultP0404P0404: the exhaust recirculation valve reading doesn't add upP0405P0405: the EGR position sensor signal is reading too lowP0406P0406: the EGR position sensor signal is reading too highP0407P0407: the EGR system's second position sensor is reading too lowP0408P0408: the EGR system's second position sensor is reading too highP0420P0420: the catalytic converter isn't cleaning up well enoughP0421P0421: the warm-up catalyst isn't cleaning up well enoughP0430P0430: bank 2's catalytic converter isn't cleaning up well enoughP0431P0431: bank 2's warm-up catalyst isn't cleaning up well enoughP0440P0440: the fuel vapour system has a faultP0441P0441: the fuel vapour system isn't purging the way it shouldP0442P0442: there's a small leak in the fuel vapour systemP0443P0443: the fuel vapour purge valve circuit has a faultP0446P0446: the fuel vapour system's vent valve circuit has a faultP0455P0455: there's a large leak in the fuel vapour systemP0456P0456: there's a very small leak in the fuel vapour systemP0457P0457: the fuel cap is loose, off, or not sealingP0480P0480: the cooling fan's control circuit has a fault