'85-'87 Civic/CRX SI ECU codes

This information is taken directly from my manual.


To view self-diagnostic information from the ECU memory you must watch the LED display on the ECU. The ECU is located under the passenger seat on '85-'87 models. With the ignition on the ECU will display four bulbs that flash in a variety of combinations. When the ECU sets a trouble code, the PGM-FI light will come on and a trouble code will be stored in the memory. The trouble code will be stored in the ECU memory until the voltage to the ecu is interrupted. Removing the HAZARD fuse in the main fuse panel for 10 seconds will clear all stored trouble codes. Trouble codes should always be cleared after repairs have been completed.

Note: To prevent damage to the ECU, the ignition must be off when disconnecting or connecting power to the ECU (this includes connecting and disconnecting the battery).

Led display ___ Symptom

1. 0 0 0 0 ____ Engine will not start
(Dash light on)
2. 0 0 0 0 ____ Engine will not start
(Dash light on)
3. 0 0 0 1 ____ Erratic idling

4. 0 0 2 0 ____ System does not operate

5. 0 0 2 1 ____ Fuel fouled plugs, engine stalls or hesitation

6. 0 4 0 0 ____ System does not operate

7. 0 4 0 1 ____ Hesitation, fuel fouled plug or engine stalls frequently

8. 0 4 2 0 ____ High idle speed durring warm-up, continued high idle or hard starting at low temperature

9. 0 4 2 1 ____ Poor engine response when operating throttle rapidly, high idle speed or engine does not rev when cold

10. 8 0 0 0 ___ Engine does not rev up, high idle speed or erratic idling

11. 8 0 0 1 ___ Same as above

12. 8 0 2 0 ___ High idle speed or erratic idling when very cold

13. 8 0 2 1 ___ Continued high idle speed

14. 8 4 0 0 ___ System does not operate at all

15. 8 4 0 1 ___ Poor acceleration at high altitude when cold

16. 8 4 2 0 ___ System does not operate at all

17. 8 4 2 1 ___ Same as above


Possible cause

1. Check for a disconnected control unit ground connector. Also check for a loose connection at the ECU main relay resistor. Possibly faulty ECU.

2. Check for a short circuit in the combination meter or warning light wire. Also check for a disconnected unit groung wire. Possibly faulty ECU.

3. Shorted or open circuit in the oxygen sensor circuit or faulty oxygen sensor

4. Faulty ECU

5. Check for a disconnected MAP sensor coupler or an open circuit in the MAP sensor wire. Also check for a faulty MAP sensor.

6. Faulty ECU

7. Check for disconnected MAP sensor vacuum hose.

8. Check for a disconnected coolant temperature sensor connector or an open circuit in the coolant temperature sensor wire. Also check for a faulty coolant temperature sensor.

9. Check for a disconnected throttle angle sensor connector. Also check for an open circuit in the throttle angle sensor wire. Possible faulty angle sensor.

10. check for a short or an open circuit in the crank angle sensor wire. Spark plug wires interfering with the crank angle sensor wire. Possible faulty crank angle sensor.

11. Same as above

12. Check for a disconnected intake air temperature sensor or an open circuit in the intake air temperature sensor wire. Possible faulty intake air temperature wire.

13. Check for a disconnected idle mixture adjuster sensor coupler or an open circuit in the idle mixture adjuster sensor wire. Possible faulty idle mixture adjuster sensor.

14. Faulty ECU

15. Check for a disconnected atmospheric pressure sensor coupler or an open circuit in the atmospheric pressure sensor wire. Possibly faulty atmospheric pressure sensor.

16. Faulty ECU

17. Same as above

Thanks for this post!

Hey for number 10 you say crank angle sensor... what the hell is that???? i couldn't find reference to that anywhere??? Autozone didn't know what it was! hahahahaha let me know man cuz i'm in really bad need of whatever that is LOL :banghead:

I believe it has to do with your distributor.... Not for certain, since I'm not staring at my manual currently... You can check the plug with an ohm-meter... I'll have to wait till I get home to finish this post...

My PGM-FI light is not on. But the ECU LED returned:

8-4-x-1

Which is number #15.

But under the sympton it says: Poor accleration at high altitudes or trouble during a cold start. It says to check the atmospheric sensor...? Where exactly can this be located?

But I don't think that this is my problem. The car won't start at all. The timing is on. The alternator is good. The battery is good. I can't really check the distributor because one of the screws holding the cap on is messed up, I can't get any bite on it. I'm at a total loss as to the problem...

What's the easiest way to get to the starter? Isn't it on the firewall side of the engine?

Thanks in advance.

mine is xxx1 eratic idle? what would be the cause of that?

Erratic idle is an O2 Sensor code. You'd wanna check that out, and if it's ok, then there might be another thing you can check. Try http://www.redpepperracing.com/technical

i have number 3!
how do you check for the Shorted or open circuit in the oxygen sensor circuit or faulty oxygen sensor???????

Bump

my ecu reads 8x21 what can i do???:confused:

I have a 85 Crx I have replaced the main relay when I start my car the PGMFI light comes on but the ECU does not flash anything at me car runs fine while the light is on about 20 minutes of it running the light turns off and the car falls on its face and dyes when you try to give it any gas. When the light flashes you can hear the relay clicking every time. Any ideas is appreciated