- Faulty EGR valve
- Leaking EGR valve gasket
- Dirty EGR passages
- Bad EGR vacuum modulator valve
- Bad EGR temperature sensor
To solve the P0402 code on your 98 Accord, you will need to:
1. Inspect the EGR valve for damage or wear. If the valve is damaged or worn, it will need to be replaced.
2. Inspect the EGR valve gasket for leaks. If the gasket is leaking, it will need to be replaced.
3. Clean the EGR passages. The EGR passages can become clogged with carbon deposits, which can restrict the flow of exhaust gas. To clean the EGR passages, you will need to remove the EGR valve and use a cleaning solvent to remove the carbon deposits.
4. Replace EGR Vacuum Modulator Valve. To clean the EGR passages, you will need to remove the EGR valve and use a cleaning solvent to remove the carbon deposits.
5. Check EGR temperature sensor. This can usually be done by unplugging the sensor at the connector and measuring resistance between the sensor's terminals. If the resistance is outside the specified range, the sensor needs to be replaced.
Once you have completed these steps, the P0402 code should be cleared and the check engine light should turn off. If the code persists, you may need to have the vehicle diagnosed by a qualified mechanic.
