How to Resolve the P0404 Trouble Code?
2 Answers
Follow the EGR monitoring screen to confirm whether the indicated opening degree and the actual follow-up value have significant deviations. If the deviation is within 5%, it indicates a normal condition, and you can simply clear the trouble code. If it does not meet the specification, it suggests that the EGR valve may be faulty, and you should proceed with inspection, repair, or direct replacement of the entire EGR valve.
I've encountered the P0404 trouble code several times, which indicates an EGR system control issue, possibly caused by a stuck valve or wiring problems. I'll first check the vacuum lines for leaks or blockages, as this is the most common cause. Then, I'll use an OBD scanner to read the data stream and see if the position sensor voltage is abnormal. If the voltage is too high or too low, I'll inspect the wiring harness connectors for looseness or corrosion. If the valve is dirty, removing it and spraying it with professional cleaner should do the trick. Regular maintenance can prevent this issue, such as checking EGR components every 20,000 kilometers. Finally, after repairs, restart the vehicle to test. Only consider replacing parts if the problem persists. Before starting, remember to measure the current with a multimeter—skipping steps might lead to missing details.
