Code No.15 Oxygen Sensor; Code No.17 Feedback System - Mazda MX-5 1990 Workshop Manual

F
SELF-DIAGNOSIS FUNCTION
CODE NO.15 OXYGEN SENSOR
Note
• If Code Nos.15 and 17 are both present, first perform the checking procedure for Code No.17
STEP INSPECTION
1 Are there any poor connections in oxygen sensor Yes
circuit?
No
2 Is oxygen sensor output voltage OK? Yes
(Refer to page F-138)
No
3 Is there continuity between oxygen sensor and ECU ter- Yes
minal2N?
No
4 Is ECU terminal 2N voltage OK?
Yes
No
5 Is sensitivity of oxygen sensor OK? Yes
(Refer to page F-138)
No
CODE NO.17 FEEDBACK SYSTEM
STEP INSPECTION
1 Warm up engine and run it at 2,500-3,000 rpm for 3 min.
2 Does monitor lamp of Self-Diagnosis Checker illuminate Yes
at idle?
No
3
Are spark plugs clean? Yes
No
4 Is oxygen sensor voltage OK? (Refer to page F-138) Yes
No
5 Is same Code No. present after performing after-repair Yes
procedure? (Refer to page F-88)
No
6 Is there continuity between oxygen sensor and ECU ter-
Yes
minal2N?
No
7 Is ECU terminal 2N voltage OK? (Refer to page F-127) Yes
No
Circuit Diagram
OXYGEN SENSOR
F-86
B (F)
GY (F)
B/LG (F)
---------~----
---
ACTION
Repair or replace connector
Go to next step
Go to next step
Replace oxygen sensor (Refer to page F-138)
Go to next step
Check for open circuit in wiring from oxygen
sensor to ECU
Go to next step
Check for short circuit in wiring from oxygen
sensor to ECU
Replace ECU (Refer to page F-127)
Replace oxygen sensor (Refer to page F-138)
05UOFX-086
ACTION
Go to next step
Check for air leak in vacuum hoses or emission
components
Check for contaminated oxygen sensor
Check for insufficient fuel injection
Go to next step
Clean or replace spark plugs
Go to next. step
Replace oxygen sensor (Refer to page F-138)
Go to next step
Check for short circuit in wiring from oxygen
sensor to ECU terminal 2N
Go to next step
Check for open circuit in wiring from oxygen
sensor to ECU
Replace ECU (Refer to page F-127)
Check for short circuit in wiring from oxygen
sensor to ECU
05UOFX-087
ECU
05UOFX-088