Questions and Answers

Accord EGR System Q. Hello, Vincent, I wrote to you before regarding a EGR problem with my 1987 Honda Accord, LXi, Fuel-Injection. I really need your help again. The car has the PGM-FI light lights up with a DTC 12. I understand this code refer to a EGR problem. Recently, I changed the EGR valve and its lift sensor (they come together in one piece).

After I installed the new EGR valve and start the car again, the light was gone. I thought I fixed the problem. However, when I took the car out for a test drive, the light came up again after several minutes of driving. Now, the EGR problem still exists. What else should I do diagnose which part of the EGR system is having problem? How many components are involved in the EGR system for this car? If possible, would you please send me a complete instruction on how to check each components in order to find out the problem?

Thank you very much!

A. This is how the EGR system works. The Electronic Control Unit (ECU) contains memories for ideal EGR valve lifts for varying operating conditions. The EGR valve lift sensor detects the amount of EGR valve lift and sends the information to the ECU. The ECU then compares it with the ideal EGR valve lift which is determined by data sent from the other sensors. If there is any difference between the two, the ECU triggers the EGR control solenoid valve to reduce the vacuum applied to the EGR valve.

Since you already replaced the EGR valve/lift sensor, that leaves a broken vacuum line, the EGR control solenoid valve or the ECU that could be the cause. To test the EGR control solenoid valve you need a special test harness.

Additional Information provided courtesy of ALLDATA