Honda Civic OBD 1 (OBD1) Codes and Tutorial
Trouble codes are displayed by the malfunction indicator lamp (MIL).
Switch ignition ON. If MIL illuminates to indicate a fault but no trouble codes are stored, suspect DLC/MIL wiring, MIL or ECM.
Some models 1997 : The ECM fault memory can also be checked using diagnostic equipment connected to the 5-pin data link connector (DLC), type 3.
All models 1999 : The ECM fault memory can also be checked using diagnostic equipment connected to the 5-pin data link connector
(DLC), type 3, or 3-pin data link connector (DLC), type 4 or 5.
Accessing
Ensure ignition switched OFF.Bridge 2-pin data link connector (DLC) terminals - type 1 & 2 Fig. 1 .
NOTE: DO NOT bridge 3 or 5-pin data link connector (DLC) terminals.
- Switch ignition ON.
- Count MIL flashes. Note trouble codes. Compare with trouble code table.
NOTE: No trouble codes stored if MIL illuminates continuously.
- Individual short flashes display trouble code Fig. 2
- A short pause separates each flash Fig. 2
- A long pause separates each trouble code Fig. 2 [C].
- For example: Trouble code 3 displayed Fig. 2 .
- Trouble codes greater than 9 are indicated as follows:
- Long flashes indicate the 'tens' of the trouble code Fig. 3 [A].
- Short flashes indicate the 'units' of the trouble code Fig. 3 [C].
- A short pause separates each flash Fig. 3 [B].
- A long pause separates each trouble code Fig. 3 [D].
- For example: Trouble code 12 displayed Fig. 3 .
- Switch ignition OFF.
- Rectify faults as necessary.
NOTE: If a trouble code is displayed but not listed in the trouble code table, suspect engine control module (ECM) fault.
Erasing
Switch ignition OFF. Remove bridge wire.
Remove BACK UP (RADIO) fuse (7,5A) from underbonnet fusebox for 10 seconds minimum:
D14A2, D14A5, D14A7, D14A8, D15B2, D15B7, D15Z1, D15Z3, D15Z8, B16A2 ->1995, D16B2, D16Y2, D16Y3, D16Y7,
D16Y8, D16Z6, D16Z7, D16Z9, B18C4 - Fig. 4 .
D14A3, D14A4, D15Z6, B16A2 1995 , D16Y5 - Fig. 5 .
Refit fuse.
Trouble codes may also be erased by disconnecting battery lead.
WARNING: Disconnecting BACK UP fuse or battery may erase memory from electronic units (e.g. radio, clock).
Trouble code identification
|
Flash type
|
Fault location
|
Probable cause
|
|
1
|
Heated oxygen sensor (HO2S)/oxygen sensor (O2S)
|
Fuel pressure/pump, wiring short to earth/open circuit/short to positive,
HO2S/O2S, ECM
|
|
3
|
Manifold
absolute pressure
(MAP) sensor
- circuit
|
Wiring,
supply voltage,
MAP sensor, ECM
|
|
4
|
Engine
speed (RPM)
sensor
|
Wiring,
RPM sensor, ECM
|
|
5
|
Manifold
absolute pressure
(MAP) sensor
- signal
|
Intake
leak, vacuum
hose blocked,
wiring, MAP
sensor, ECM
|
|
6
|
Engine
coolant temperature
(ECT) sensor
|
Wiring
short to
earth/open circuit,
ECT sensor, ECM
|
|
7
|
Throttle
position (TP)
sensor
|
Wiring
short to
earth/open circuit,
TP sensor, ECM
|
|
8
|
Crankshaft
position (CKP)
sensor
|
CKP
sensor, wiring
short to
earth/open circuit,
ECM
|
|
9
|
Camshaft
position (CMP)
sensor
|
CMP
sensor, wiring
short to
earth/open circuit,
ECM
|
|
10
|
Intake
air temperature (IAT)
sensor
|
Wiring
short to
earth/open circuit,
IAT sensor, ECM
|
|
12
|
Exhaust
gas recirculation (EGR)
system -
control
|
Wiring, vacuum hose(s), EGR solenoid, EGR valve position sensor,
EGR valve, ECM
|
|
14
|
Idle
air control (IAC)
valve -
circuit
|
Wiring,
supply voltage,
IAC valve, ECM
|
|
15
|
Ignition
amplifier -
control circuit
|
Wiring,
supply voltage,
ignition amplifier,
ECM
|
|
16
|
Injectors
|
Wiring,
supply voltage,
injector, ECM
|
|
17
|
Vehicle
speed sensor
(VSS)
|
Wiring,
VSS, ECM
|
|
19
|
Transmission
lock-up solenoid
|
Wiring,
solenoid, ECM
|
|
20
|
Electrical
load sensor
|
Wiring,
electrical load
sensor, ECM
|
|
21
|
Camshaft
position (CMP)
actuator
|
Wiring,
CMP actuator, ECM
|
|
22
|
Camshaft position (CMP) actuator oil pressure switch
|
Wiring,
CMP actuator oil
pressure switch,
ECM
|
|
23
|
Knock
sensor (KS)
|
Wiring,
KS, ECM
|
|
41
|
Oxygen
sensor heater
- circuit malfunction
|
Wiring
short to
earth/open circuit/short
to positive, HO2S,
ECM
|
|
43
|
Heated oxygen sensor (HO2S)/fuel supply system - circuit
malfunction
|
Wiring,
fuel pressure/pump/filter,
injector, HO2S,
ECM
|
|
48
|
Heated oxygen sensor (HO2S) - circuit malfunction
|
Wiring,
HO2S, ECM
|
|
54
|
Engine
speed fluctuation
sensor
|
Wiring,
engine speed
fluctuation sensor,
ECM
|
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