My 1984 Toyotoa EXcab pickup, EFI, manual tran, failed the Calif. Smog vehicle inspection. It first failed the CO % measurement in the 15 mph test, but passed the 25 mph test. The technician retested it, and it failed in the
25 mph test, but passed the 15 mph test. I first had the Oxygen sensor replaced (cost $187.00), but it still didn't pass. Now, the mechanic says the "systems modulator" needs replacing. I went to an auto parts store and the clerk says he doesn't know if the mechanic means EGR value, or EGR vacuum modulator. The EGR valuve was $160, but I didn't get a price on a vacuum modulator.
If the vacuum modulator is the problem, my Toyota manual makes it look easy enough to replace.
The mechanic wants $297 to replace whatever this systems modulator is.
Any suggestions?