Code 12, EGR System
- Check harness and connections between EGR valve and ECU. Verify vacuum supply to EGR control solenoid. Check vacuum hoses for cracks, splits or looseness. Repair as necessary. Warm engine to normal operating temperature (cooling fan on). Disconnect vacuum hose from EGR valve. Using a hand-held vacuum pump, apply vacuum to EGR valve. If vacuum does not hold, and engine does not stall, replace faulty EGR valve or clean blocked EGR passages.
- If vacuum held and engine stalled in step 1), turn ignition off. Disconnect 6-wire connector on right side of firewall. See Fig 1
. Disconnect vacuum hoses from EGR solenoid. Apply vacuum to one side of EGR solenoid. Vacuum should hold. On solenoid side of sensor harness, jumper battery voltage to Yellow/Black wire and battery ground to White wire. Solenoid should energize and vacuum should bleed off. If solenoid does not respond as described, replace faulty solenoid.
- If solenoid is okay, reconnect vacuum hoses. Turn ignition on. Check voltage between ground and Black/Yellow wire terminal on harness side of connector. If battery voltage is not present, repair open in wire between harness connector and No. 9 fuse. If battery voltage is present, turn ignition off.
- Connect inspection adaptor between EGR valve lift sensor connector and harness connector. Turn ignition on. Measure voltage between Red (pos.) and Green (neg.) terminals. If reading is not about 5 volts, go to step 7). If voltage is about 5 volts, measure voltage between White (pos.) terminal and Green (neg.) terminal. If voltage is not about one volt, turn ignition off. Connect system checker harness between ECU and ECU connector.
- Turn ignition on. Measure voltage between terminals C8 (pos.) and C14 (neg.). If reading is not about one volt, repair open in White/Green wire between ECU terminal C8 and EGR sensor. If reading was about one volt, disconnect "A" connector from the ECU only, not the right side wire harness.
- Measure voltage between terminals A10 (pos.) and A18 (neg.). If battery voltage is not present, repair open White wire between ECU terminal A10 and EGR control solenoid. If battery voltage is present, substitute a known good ECU. If condition is rectified, replace original ECU.
- If voltage reading between Red (pos.) and Green (neg.) terminals in step 2) was not about 5 volts, measure voltage between ground and Red terminal. If reading is about 5 volts, repair open Green/White wire between ECU terminal C14 and sensor. If voltage is still not about 5 volts, turn ignition off. Connect system checker harness between ECU and ECU connector. Turn ignition on. Measure voltage between terminals C13 (pos.) and C14 (neg.).
- If reading is about 5 volts, repair open Yellow/White wire between ECU terminal C13 and sensor. If reading is not about 5 volts, substitute a known good ECU. If condition is rectified, replace original ECU.
Courtesy of AMERICAN HONDA MOTOR CO., INC.