Articles » OBD0 Check Engine Light (CEL) Codes

When the Check Engine warning light has been reported on, turn the ignition on, pull down the passenger's side carpet from under the dashboard and observe the LED on the top of the ECU. The LED indicates a system failure code by blinking frequency. The ECU LED can indicate any number of simultaneous component problems by blinking seperate codes, one after another. Problem codes 1 through 9 are indicated by individual short blinks. Problem codes 10 through 44 are indicated by a series of long and short blinks. One long blink equals 10 short blinks. Add the long and short blinks together to determine the problem code.

you have to jump a service connector located on the passenger side right under the dashboard near the door. The connector has two pin inputs. Connecting them with something like a paper clip will force the check engine light on the dashboard to display the codes. when u pull the kick panel on the right side floor board where your ecu you there will be an extra plug hanging i beleive its green or blue, put the paper clip in it, turn the ignition to the on position and count the number of blinks on the check engine light.

codes 1-9 are indicated by a series of short flashes; two digit codes use a number of long flashes for the first digit followed by the number of short flashes for the second digit. So a code 43 will be represented by 4 long and 3 short flashes.

The position of codes in a sequence can be helpful in doing diagnostics. A display showing 1-1-1-pause-9-9-9 indicates two problems occurring at different times. A sequence showing 1-9-1-9-1-9 indicates two problems occurring at the same time.


Note: OBD0 is for ECUs in the years 1988 - 1991.

Self-Diagnosis Indicator Blinks	System Indicated
0	ECU
1, 2	Oxygen Content
3	Manifold Absolute Pressure
5
4	Crank Angle
6	Coolant
7	Throttle Angle
8	TDC Position
9	No. 1 Cylinder Position
10	Intake Air Temperature
13	Atmospheric Pressure
14	Electronic Air Control
15	Ignition Output Signal
17	Vehicle Speed Sensor
21	Spool Solenoid Valve
22	Oil Pressure Switch
43, 44	Fuel Supply System (KX, KS, KG)

If codes other than those listed above are indicated, count the number of blinks again. If the indicator is in fact blinking unusual codes, subsitute a known-good ECU and recheck. If the indication goes away, replace the original ECU. The Check Engine warning light and ECU LED may come on, indicating a system problem, when, in fact, there is a poor or intermittent electrical connection. First, check the electrical connections, clean or repair connections if necessary. If the Check Engine warning light is on and LED stays on, replace the ECU.




this was taken from the Helms manual for 88-91 Civics.

Author: Anonymous
Date: Apr 14, 2003
Views: 10,367