HOW TO: Check And Fix ECU Trouble Codes With Pics

[ShyBoyCA6]

I had an idea to add pictures to help verify and locate the problem. I will add pictures tomorrow for everything that i listed here to help confusion and the new guys. Mods Please feel free to sticky this if you like. Will update the thread with OBD1 Trouble Codes when i do my Obd1 swap.

How to check your ECU codes:
1. Move Driver seat all the way forward.

2. Locate the Cover Flap on the ECU Cover.(Mine doesn't have the cover, yours should have a cover on it unless you removed it.)

3. Turn the Ignition on.(Position 2)

4. Open Flap and Look at the plastic glass.

5. Count how many times the Led flashes.
6. Below are the Flash codes and what to check for.

For double digits it will blink once for 1 and pause and flash again for the second number.

ECU CODES for 86-89 Honda Accord and 85-89 Honda Prelude.

00 LED FLASH(s) ECU
Led will be on and steady with no flashes.

What To Do: Replace Ecu with another one

01 LED FLASH(s) 85-98 Accord
Oxygen Sensor "A" (Primary)
Defective Circuit Or Unplugged / Defective Sensor

What To Do: Replace O2 Sensor with a new one.
What To expect with this Code: Car will have bad MPG/Run like crap. If going the same speed for a certain amount of time the light will go off and car will run rich.
Location: O2 Sensor "A" Is located on the LEFT and the color where it goes is GREEN. If Connected in the wrong place car will not run right and problem will occur again.

02 LED FLASH(s) 85-89 Accord
Oxygen Sensor "B"
Defective Circuit Or Unplugged / Defective Sensor

Same as O2 "A" repeat the steps.
Location: O2 Sensor "B" Is Located on the RIGHT and color where it goes is WHITE.

03 LED FLASH(s) 85-98 Accord
MAP Sensor (Manifold Absolute Pressure)
Defective Circuit Or Unplugged / Defective Sensor

04 LED FLASH(s) Crank Angle

05 LED FLASH(s) 85-98 * Accord
MAP Sensor (Manifold Absolute Pressure)
Mechanical Problem / Disconnected Piping
* exc. 94-95

06 LED FLASH(s) 85-98 Accord
E.C.T Sensor (Engine Coolant Temperature)
Defective Circuit Or Unplugged / Defective Sensor

Location: WHITE one On the RIGHT.
What To Do: Check Wires and Connections
What to expect: Hard To Start and Tach will Act funny.

07 LED FLASH(s) 85-98 Accord
T.P Sensor (Throttle Position)
Defective Circuit Or Unplugged / Defective Sensor

08 LED FLASH(s) 85-98 Accord
T.D.C Sensor (Top Dead Center)
Defective Circuit Or Unplugged / Defective Sensor

09* LED FLASH(s) 85-98** Accord
CYP Sensor (Cylinder)
Defective Circuit Or Unplugged / Defective Sensor
* Not a valid code for any throttle body injection Hondas
** Not a valid code for V-6 engines

10 LED FLASH(s) 85-98 Accord
IAT Sensor (Intake Air Temperature)
Defective Circuit or Unplugged / Defective Sensor

12 LED FLASH(s) 85-98 Accord
EGR Lift Sensor (Exhaust Gas Recirculation)
Defective Circuit Or Unplugged / Defective Sensor

13 LED FLASH(s) 85-98 Accord
BARO Sensor (Atmospheric Pressure)
Defective Circuit Or Unplugged / Defective Sensor

Location: Passenger side behind the DASH
What To Do: Replace sensor and check connection/If removed Trouble code will appear

14 LED FLASH(s) 88-98 Accord
IAC Valve (Idle Air Control)
Defective Circuit Or Unplugged / Defective Sensor
IAC VALVE HELP

15 LED FLASH(s) Ignition Output Signal

16 LED FLASH(s) Fuel Injector

What To Do: Inspect wires and Connection/ Test Fuel Injector Or Replace/ Check Fuse Under Hood its A 10A.

17 LED FLASH(s) 88-98 Accord
VSS (Vehicle Speed Sensor)
Defective Circuit Or Unplugged / Defective Sensor

[A18A]

this is already one of teh stickys in the efi section lol https://www.3geez.com/forum/efi-tech/...heck-them.html

[2oodoor]

Shyboy, anything you can create to enhance even existing knowledge base, especially pictures, is great. Just follow up with a mod so somebody knows where it is and we can check it out. That does look like a copy paste of the existing thread though.

[King Peetis]

Keep it going. We can never have too much information...Lots of pics..Good work!

[Rendon LX-i]

Update is always nice. A lot of info is fail without pics. Remove all sticky an apply this one lol

[ShyBoyCA6]

Oh? i had copied this off the net and had this in a saved file on my computer lol. well i see your point A18A i guess ill add more info on what to look for and diagnose the problem Pictures will be coming on tonight with added info. Thanks for the tip roodoo im not taking any credit in this as i only wanna help the community answer their question and understand it better as much i can explain it to them.

Why is that we can only add ten Photos per post? figure since the new update we should be able to post more? Would like to know more on this.

[ronniman]

Great thread Thanks for the info currently trying to figure out why my car won't start. Any chance you know what it means if you ecu shows no lights at all when in the ll position? I've been searching but cannot find the answer, in thinking either is a good thing or is dead.

[ShyBoyCA6]

Great thread Thanks for the info currently trying to figure out why my car won't start. Any chance you know what it means if you ecu shows no lights at all when in the ll position? I've been searching but cannot find the answer, in thinking either is a good thing or is dead.

Thanks just trying to help as much as i can and um to answer your question have you check your fuses by any chance? Also it helps to have someone to check and put the key in position II while they/you look. it will blink fast probably like 2 seconds. When you say "My car won't start" what exactly is it doing? we need more details to help you find the problem.

[ronniman]

Thanks just trying to help as much as i can and um to answer your question have you check your fuses by any chance? Also it helps to have someone to check and put the key in position II while they/you look. it will blink fast probably like 2 seconds. When you say "My car won't start" what exactly is it doing? we need more details to help you find the problem.

Great point on having multiple people however I did have my fiance turn the key while I looked and no light comes on at all, I checked all fuses none were blown I'm going to check for spark tonight been fighting off bronchitis so havnt been able to do much if interested I have a thread on it already but don't mind checking back here for a response either but just incase so you can get the full scoop https://www.3geez.com/forum/technical...ont-start.html

[2oodoor]

E

Why is that we can only add ten Photos per post? figure since the new update we should be able to post more? Would like to know more on this.

I don't know, its just a learning process of the formats developed by the rulers of the universe.
Just open more tabs and move them into posts, even if it takes multiple posts. It helps to jot down the last 4 # of the file and assign a breif narrative so you remembr the order when you drag them. Pm me if you want.

[Dr_Snooz]

Great thread Thanks for the info currently trying to figure out why my car won't start. Any chance you know what it means if you ecu shows no lights at all when in the ll position? I've been searching but cannot find the answer, in thinking either is a good thing or is dead.

Does the Check Engine light on the dash come on for 2 seconds when you first turn on the key? If so, the ECU is fine.

[Dr_Snooz]

I copied this to the How-To section. Nice work, Shyboy!

[ShyBoyCA6]

I copied this to the How-To section. Nice work, Shyboy!

Thank you Dr.Snooz. I would be taking the other pics to add and finish it

[ronniman]

Does the Check Engine light on the dash come on for 2 seconds when you first turn on the key? If so, the ECU is fine.

Hey sorry took so long to reply been really sick, anyways might be a stupid question but I have never seen a"check engine"light on my dash come on are you referring to the PGMFI light? If so yes that comes on for a few seconds and shuts off.

[hondasRus]

Great job with all the post new.guy here quick question as I am playing hell trying to fine out what it is or where.to fond it. Anyways in the picture with the thermo denser what is the green one next to it? Thanks