DTC P1381 & DTC P1382 - CYP SENSOR Honda Prelude V

1. Perform PCM reset procedure. See «TESTS W/CODES - INTRODUCTION»(ref-16345) article. Start engine. If DTCs P1381 and/or P1382 are indicated, go to next step. If DTCs P1381 and/or P1382 are not indicated, problem is intermittent. System is okay at this time. Check for poor connections or loose wires between distributor/CYP sensor 4-pin connector and PCM. See «WIRING DIAGRAMS»(ref-16355) article.
2. Turn ignition off. Disconnect distributor/CYP sensor 4-pin connector. Measure resistance between distributor/CYP sensor terminals No. 2 (Yellow wire) and No. 4 (Black wire). see scheme 8 If resistance is 260-460 ohms, go to next step. If resistance is not 260-460 ohms, replace distributor ignition housing.
3. Check for continuity between ground and distributor/CYP sensor terminals No. 2 (Yellow wire) and No. 4 (Black wire), individually. see scheme 8 If continuity does not exist, go to next step. If continuity exists, replace distributor ignition housing.
4. Ensure ignition is off. Reconnect distributor/CYP sensor 4-pin connector. Disconnect PCM 31-pin connector "C". see scheme 3 Measure resistance between PCM 31-pin connector "C" terminal C4 (Yellow wire) and terminal C14 (Black wire). If resistance is 260-460 ohms, go to next step. If resistance is not 260-460 ohms, repair open in suspect wire(s) between distributor/CYP sensor and PCM. See «WIRING DIAGRAMS»(ref-16355) article.
5. Check for continuity between ground and PCM 31-pin connector "C" terminal C4 (Yellow wire). If continuity exists, repair short in wire between distributor/CYP sensor and PCM. See «WIRING DIAGRAMS»(ref-16355) article. If continuity does not exist, substitute a known-good PCM and recheck. If symptom or problem goes away, replace original PCM.

Scheme 29

Scheme 30

1. If either DTC P1456 or DTC P1457 sets, check for: A faulty fuel filler cap. Proper vacuum connections. Fuel tank leak. EVAP control canister vent shut valve malfunction. EVAP control canister vent shut valve circuit malfunction. EVAP purge control solenoid valve malfunction. EVAP purge control solenoid valve circuit malfunction. EVAP by-pass solenoid valve malfunction. EVAP by-pass solenoid valve circuit malfunction. Fuel tank pressure sensor malfunction. Fuel tank pressure sensor circuit malfunction. EVAP control canister malfunction. Repair as necessary. If no problems are found, go to next step.
2. Disconnect vacuum hose from EVAP 3-way valve. (Scheme 29) See «VACUUM DIAGRAMS»(ref-16356) article. Connect vacuum pump/gauge to hose. Turn ignition on. Apply vacuum to hose (5 quick strokes). If vent shut valve does not hold a vacuum, go to next step. If vent shut valve holds a vacuum, disconnect vent shut valve 2-pin connector. If vent shut valve holds a vacuum, replace vent shut valve. If vent shut valve does not hold a vacuum, repair short in Orange/Green wire between vent shut valve and PCM 32-pin connector "A" terminal A29. see scheme 1 See «WIRING DIAGRAMS»(ref-16355) article.
3. Turn ignition off. Using backprobe set, connect a fused jumper wire between ground and PCM 32-pin connector "A" terminal A29 (Orange/Green wire). see scheme 1 Turn ignition on and apply vacuum to vent shut valve vacuum hose. If vent shut valve holds a vacuum, go to step 6). If vent shut valve does not hold a vacuum, go to next step.
4. Turn ignition off. Disconnect vent shut valve 2-pin connector. Turn ignition on. Measure voltage between ground and vent shut valve 2-pin connector Black/Yellow wire. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Black/Yellow wire between vent shut valve and No. 14 ECU/EAT ECU (15-amp) fuse located in underdash fuse/relay box. See «WIRING DIAGRAMS»(ref-16355) article.
5. Turn ignition off. Reconnect vent shut valve 2-pin connector. Turn ignition on. Using backprobe set, measure voltage between PCM 32-pin connector "A" terminal A10 (Black wire) and terminal A29 (Orange/Green wire). see scheme 1 If battery voltage does not exist, repair open in circuit between vent shut valve and PCM connector terminal A29. See «WIRING DIAGRAMS»(ref-16355) article. If battery voltage exists, replace EVAP control canister vent shut valve.
6. Reconnect vacuum hose to EVAP 3-way valve. Disconnect EVAP purge control solenoid valve vacuum hose from EVAP canister (lower left hose). (Scheme 29) See «VACUUM DIAGRAMS»(ref-16356) article. Connect vacuum pump/gauge to disconnected hose. Start engine and allow it to idle. Ensure engine coolant temperature is less than 122°F (50°C). Quickly increase engine speed to 3000 RPM and check for vacuum. If vacuum does not exist, go to step 9). If vacuum exists, go to next step.
7. Disconnect EVAP purge control solenoid valve 2-pin connector. Quickly increase engine speed to 3000 RPM and check for vacuum. If vacuum does not exist, go to next step. If vacuum exists, inspect vacuum hose routing. See «VACUUM DIAGRAMS»(ref-16356) article. If okay, replace EVAP purge control solenoid valve.
8. Turn ignition off. Disconnect PCM 32-pin connector "A". Check for continuity in Red/Yellow wire between ground and EVAP purge control solenoid valve 2-pin connector. If continuity exists, repair short in Red/Yellow wire between EVAP purge control solenoid valve connector and PCM 32-pin connector "A" terminal A15. See «WIRING DIAGRAMS»(ref-16355) article. If continuity does not exist, substitute a known-good PCM and recheck. If symptom or problem goes away, replace original PCM.
9. Run engine at 3000 RPM with no loads and transmission in Park or Neutral until radiator fan comes on. Allow engine to idle. Quickly increase engine speed to 3000 RPM and check for vacuum at EVAP purge control solenoid valve vacuum hose. If vacuum does not exist, go to next step. If vacuum exists, go to step 13).
10. Turn ignition off. Disconnect EVAP purge control solenoid valve 2-pin connector. Turn ignition on. Measure voltage between ground and EVAP purge control solenoid valve 2-pin harness connector terminal No. 2 (Black/Yellow wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Black/Yellow wire between EVAP purge control solenoid valve connector and No. 14 ECU/EAT ECU (15-amp) fuse located in underdash fuse/relay box. See «WIRING DIAGRAMS»(ref-16355) article.
11. Turn ignition off. Reconnect EVAP purge control solenoid valve 2-pin connector. Turn ignition on. Using backprobe set, measure voltage between PCM 32-pin connector "A" terminal A10 (Black wire) and terminal A15 (Red/Yellow wire). see scheme 1 If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Red/Yellow wire between EVAP purge control solenoid valve connector and PCM 32-pin connector "A" terminal A15. See «WIRING DIAGRAMS»(ref-16355) article.
12. Turn ignition off. Using backprobe set, connect a fused jumper wire between PCM 32-pin connector "A" terminal A10 (Black wire) and terminal A15 (Red/Yellow wire). see scheme 1 Start engine and allow it to idle. Check for vacuum at EVAP purge control solenoid valve vacuum hose. If vacuum does not exist, check vacuum hose routing. See «VACUUM DIAGRAMS»(ref-16356) article. If vacuum hoses and routing are okay, replace EVAP purge control solenoid valve. If vacuum exists, substitute a known-good PCM and recheck. If symptom or problem goes away, replace original PCM.
13. Check EVAP 2-way valve. See EMISSION SYSTEMS & SUB SYSTEMS in «SYSTEM/COMPONENT TESTS»(ref-16351) article. Replace EVAP 2-way valve if faulty. If EVAP 2-way valve is okay, disconnect vacuum hoses from EVAP 2-way valve. Connect vacuum pump/gauge to EVAP 2-way valve (lower port to EVAP canister) and apply vacuum. (Scheme 30) If 2-way valve holds a vacuum, go to step 15). If 2-way valve does not hold a vacuum, go to next step.
14. Disconnect EVAP by-pass solenoid valve 2-pin connector. Apply vacuum to hose. If EVAP 2-way valve holds a vacuum, repair short in Green/White wire between EVAP by-pass solenoid valve connector and PCM 32-pin connector "A" terminal A28. See «WIRING DIAGRAMS»(ref-16355) article. If EVAP 2-way valve does not hold a vacuum, replace EVAP by-pass solenoid valve.
15. Turn ignition off. Using backprobe set, connect a fused jumper wire between ground and PCM 32-pin connector "A" terminal A28 (Green/White wire). see scheme 1 Turn ignition on and apply vacuum to EVAP 2-way valve. If EVAP 2-way valve holds a vacuum, go to next step. If EVAP 2-way valve does not hold a vacuum, check following components for leakage to atmosphere, and repair or replace as necessary: fuel filler cap, fuel tank, fuel vapor pipe, EVAP 2-way valve, EVAP by-pass solenoid valve, fuel tank pressure sensor, EVAP control canister, EVAP control canister vent shut valve, EVAP purge control solenoid valve, and vacuum hoses and connections. See «VACUUM DIAGRAMS»(ref-16356) article.
16. Turn ignition off. Disconnect EVAP by-pass solenoid valve 2-pin connector. Turn ignition on. Measure voltage between ground and EVAP by-pass solenoid valve connector terminal No. 1 (Black/Yellow wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Black/Yellow wire between EVAP by-pass solenoid valve connector and fuse No. 14 (15-amp) ECU/EAT ECU. See «WIRING DIAGRAMS»(ref-16355) article.
17. Turn ignition off. Reconnect EVAP by-pass solenoid valve 2-pin connector. Turn ignition on. Using backprobe set, measure voltage between PCM 32-pin connector "A" terminal A10 (Black wire) and terminal A28 (Green/White wire). see scheme 1 If battery voltage exists, replace EVAP by-pass solenoid valve. If battery voltage does not exist, repair open in Green/White wire between EVAP solenoid valve connector and PCM connector terminal A28. See «WIRING DIAGRAMS»(ref-16355) article.