Emission Controls Trouble Codes: List & Fixes

P0420 Powertrain The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly. Low P0430 Powertrain The bank 2 converter on a V6, V8 or split-exhaust engine isn't cleaning the exhaust well enough. Low P0442 Powertrain The EVAP system leaks through an opening of about 0.040 inch — a cracked hose, loose joint… Minor P0446 Powertrain The canister vent valve isn't doing what the ECU commands — electrically or because the vent… Minor P0456 Powertrain The EVAP system has a tiny leak, about 0.020 inch — the hardest EVAP leak to find, and often… Minor P0457 Powertrain The EVAP leak test found the system wide open — almost always a loose, missing or worn gas cap. Minor

P0455 Powertrain The fuel vapor system can't hold vacuum at all — check the gas cap first, then hoses and valves. Low P0456 Powertrain The EVAP system has a tiny leak, about 0.020 inch — the hardest EVAP leak to find, and often… Minor P0457 Powertrain The EVAP leak test found the system wide open — almost always a loose, missing or worn gas cap. Minor P0458 Powertrain The purge valve control line reads too low: lost power feed, open coil or a wire shorted… Low P0459 Powertrain The purge valve control line stays high when the ECU grounds it: a short to power or a shorted… Low P0460 Powertrain The engine computer gets no usable fuel level signal – often a tank-top connector or the sender… Low P0461 Powertrain The fuel level reading doesn't change the way fuel use says it should – usually a worn or stuck… Low P0462 Powertrain Fuel level signal voltage stuck near zero – usually a shorted sender or a signal wire rubbing… Low P0463 Powertrain Fuel level signal reads like an open circuit – most often a corroded tank-top connector… Low P0471 Powertrain The exhaust backpressure reading doesn't match what the computer expects; the sensor tube… Moderate P0472 Powertrain Exhaust backpressure sensor signal near zero volts: dead sensor, grounded wire or lost 5 V… Moderate P0491 Powertrain Too little cold-start air reached the bank 1 exhaust during the self-test; pump, combi valve… Low P0492 Powertrain The cold-start air check found too little air on the bank 2 side only, so look at that side's… Low P0496 Powertrain Vapor is being drawn into the engine while purge is commanded off: almost always a purge valve… Low P0497 Powertrain Purge is commanded but too little vapor reaches the engine: blockage, closed valve or weak… Minor P1296 Volkswagen · Powertrain The VW ECU saw coolant temperature behave differently from its model – usually a sensor… Low P1400 Ford · Powertrain The Ford PCM sees the EGR pressure-feedback (DPFE) sensor signal stuck below its normal minimum… Low P1401 Ford · Powertrain The Ford DPFE sensor that measures EGR flow is sending a voltage above anything it should… Low P1404 Chevrolet · Powertrain The electric EGR valve on a Chevy isn't fully closing when the PCM commands it shut. Low P1405 Ford · Powertrain Ford's EGR flow sensor isn't getting exhaust pressure on its upstream port: loose, split… Low P1406 Ford · Powertrain The hose between Ford's DPFE sensor and the EGR-valve side of the orifice is off, leaking… Low P1441 Chevrolet · Powertrain Engine vacuum is reaching the fuel tank even though the PCM has the EVAP purge valve turned off. Low P1444 Nissan · Powertrain Nissan's ECM sees fuel vapor flowing to the engine while the purge valve is supposed to be shut. Low P144A Ford · Powertrain Ford's EVAP test pulled vacuum too fast, meaning part of the vapor path to the fuel tank… Low P1450 Ford · Powertrain Ford's EVAP test pulled vacuum on the fuel tank and the vacuum didn't bleed off as expected. Low P1451 Ford · Powertrain Ford's PCM sees an electrical fault in the circuit of the EVAP canister vent solenoid near… Minor P1456 Honda · Powertrain Honda's EVAP test found a vapor leak on the fuel tank side of the system. Low P1457 Honda · Powertrain Honda's EVAP self-test found a leak on the charcoal canister side, not at the fuel tank or gas… Low P1494 Jeep · Powertrain Your Jeep's EVAP leak detection pump was commanded to stroke, but its internal switch never… Minor P1495 Jeep · Powertrain The PCM found an open or short in the circuit that fires your Jeep's EVAP leak detection pump… Minor