Civic L4-1.7L CNG (2003)
YES - Go to step 7.
NO - Replace the P1 fuel pressure regulator. Then disconnect the negative cable from the battery for a few seconds to reset the blinking low fuel
indicator.
7. Measure voltage between fuel pressure regulator switch 2P connector terminal No.1 and body ground.
Is there about 5 V?
YES - Go to step 8.
NO - Repair open in the wire between the fuel pressure regulator switch and PCM (E28).
8. Substitute a known-good fuel pressure regulator switch and recheck.
Does the low fuel indicator light blink?
YES - Do a leak inspection. If there is no leak, update the PCM if it does not have the latest software, or substitute a known-good PCM, then
recheck.
If the symptom/indication goes away with a known good PCM, replace the original PCM.
NO - Replace the original fuel pressure regulator switch
