Civic 1.5L A/T (California)
- Verify if CHECK ENGINE light is on and if LED is flashing Code 12. Check harness and connections between EGR valve and ECU. Check vacuum hoses for cracks, splits and looseness. Repair as necessary. Remove ECU fuse for 10 seconds to reset ECU.
- Warm engine to normal operating temperature (cooling fan on). Disconnect vacuum hose No. 16 from EGR valve. Using a hand-held vacuum pump, apply vacuum to EGR valve. If vacuum does not hold and engine does not stall, clean blocked EGR passages or replace faulty EGR valve.
- If vacuum holds and engine stalls in step 2), disconnect Constant Vacuum Control (CVC) vacuum hose, and connect to vacuum gauge. Start engine. If about 8 in. Hg is not present, check vacuum hoses and connecting pipes. If vacuum is present, reconnect hose between vacuum chamber and EGR solenoid.
- Verify vacuum supply to EGR valve. If vacuum is now present at EGR valve, check for short in Red wire between ECU terminal A10 and EGR control solenoid. If wire is okay, replace solenoid. If vacuum is not present, turn engine off. Disconnect 4-wire connector from control box. Supply battery voltage to terminal "D", and ground to terminal "C" at control box (solenoid side of harness). See Fig 1
. Start engine and check EGR valve for 8 in. Hg. If vacuum is present, go to step 6).
- If vacuum is not present, remove control box cover. Disconnect vacuum hose between air chamber and solenoid valve. Connect vacuum gauge to air chamber. Start engine. If about 8 in. Hg is not present, check hose routing of EGR system. If vacuum is present, replace CVC valve.
- Measure voltage between ground and Black/Yellow wire terminal of harness. If battery voltage is not present, repair open in Black/Yellow wire between solenoid valve and fuse No. 14. If battery voltage is present, turn ignition off. Connect Test Harness (07GMJ-ML80100) between EGR valve lift sensor and sensor connector. Disconnect vacuum hose from EGR valve.
- Turn ignition on. Measure voltage between Red (+) and Green (-) terminals of harness. If about 5 volts are indicated, go to step 10). If about 5 volts are not indicated, measure voltage between ground and Red (+) harness terminal.
- If 5 volts are indicated, repair open in Green/White wire between ECU terminal C12 and sensor. If about 5 volts are not indicated, repair open in Yellow/White wire between ECU terminal C13 and EGR valve lift sensor. If wire is okay, substitute a known good ECU. If condition is corrected, replace original ECU.
- If voltage is about 5 volts, measure voltage between White (+) and Green (-) terminals of harness. If about one volt is not indicated, replace EGR valve or repair short in Yellow wire between ECU terminal C8 and EGR valve lift sensor. If about one volt is indicated, turn ignition off.
- Connect ECU Test Harness between ECU and ECU connector. See Figure
. Turn ignition on. Measure voltage between terminals C8 (+) and C12 (-). See Figure
. If about one volt is not indicated, repair open Yellow wire between ECU terminal C8 and sensor.
- If about one volt is indicated, start engine, and allow to idle. Connect terminals A10 (+) and A2 (-) using jumper. If engine does not stall, repair open in Red wire between ECU terminal A10 and EGR control solenoid valve. If engine stalls, substitute a known good ECU, and recheck. If condition is corrected, replace original ECU.
Courtesy of AMERICAN HONDA MOTOR CO., INC.