dominguez

hey guys my problem started a couple months back when my engine light came on, i was on the highway and the car bogged down into limp mode i pulled over to check and my entire downpipe was glowing red. After letting it cool down the engine light went off and all was fine. A week later my battery light came on, my alt and batt tested out fine at that point the battery light remained on and then i heard the relay clicking where the ecu is , every time i heard the relay click the engine light came on, finally it stopped clicking and the ecu was presumed dead by the honda dealer. I replaced the ecu and had my keys flashed, all was fine. The following day i experienced the same lean out problem with the engine light and glowing downpipe, once again it was fine after minutes. A week since that battery light came back on and the same clicking came from the relay and now the engine light is back on with no tach or heat guage again and the limp mode. I guess i may have fried another ecu. There's posts on this board with similar symptoms happening ,i'm hoping that perhaps one of you may have a slight idea of whats happening and i appreciate any suggestions. thank you.

Axe Man

iTrader: (1)

Don't assume the ECU is bad just yet. See if you can get the DTC's (Diagnostic Trouble Codes) readout first. The code or codes should provide an important clue as to what is going on. Reading out the codes requires an OBD-II scan tool. Autozone will perform this service for free as long as you aren't in California. The codes are formatted PXXXX, where XXXX is series of numbers. Write down the code or codes that spit out of the ECU. Post them here. There's also a sticky as to what the codes mean.

dominguez

actually it doesn't seem that this second ecu is quite dead yet, because everytime i start the car i have a tach, then there will be a series of clicks from the relay before it stops and goes into limp mode with no tach or temp. The battery light is on during the clicks then it shuts off when the engine light becomes solid, unfortunately i don't have an obd2 scanner but i guess i could find a shop in town that would perhaps read my codes and let me document them cheaper than honda would. I spoke with one of the mechanics today at honda and he says it seems like it may be a ground problem and that the the system if it can't find a ground that it will look to the ecu for one and thats perhaps how it fried, i'm not sure if thats the case. Is there any diy's for grounding? thanks for the help

bobsagator

iTrader: (13)

Is it a DX/LX? If your downpipe was glowing red then your catalytic converter is probably toasted.

SOHC_VTEC_pwr

What you need to do is not drive it b/c you can mess sum **** up and have to pay more money. But if it is indeed a ground issue for the ecu then you can always look for diagrams to where it grounds at and check it for corrosion or a loose connection. But you need to find a really good master tech to look at it and diagnose it right the 1st time so you dont have to deal wit it all the dam time.

dominguez

it is a 02 canadian si which is a lx or ex i think in the usa, the cat is a brand new magnaflow cat that has the second o2 sensor installed in it properly, there's no way it's plugged, i'm still driving the car unfortunately......

Radianceautospa

Please tell me this was solved I have the exact identical issue

Aetoc

iTrader: (1)

Yea my car just started acting up today too...green security light flashing, engine light on, no tach, no temp gauge, hardcore limp mode, no connectivity on the diag port...anyone seen this before and fixed it?

Herman Wiegman

I think the answer to this ECU problem is covered in an other post on these forums.

332229-2001-civic-lx-lots-problems

https://www.civicforums.com/forums/3...-problems.html

I have just experienced this fault on my 2002 Civic EX
1) battery light on
2) the Check Engine Light (CEL) blips on sever times over the course of a few minutes
3) the relays click open/closed at the same time as the CEL blips
4) after ~15 or so events, the CEL stays on and the Tack and Temp gauges go to zero.
5) the engine is then in some very limited "limp home" mode

I am not sure if the green security light is associated with this ECU failure.

Note: the OBDII code reader has trouble connecting to the ECU, perhaps due to the CEL flashing on every few seconds, so no communications can be established. I was able to establish comms, but did not find any fault codes in the ECU.

This seems to be the common behavior of a faulty ECU.
The source of the ECU failure seems to be a bad ground connection with the engine block, which is found under the air box, on the front left corner of the engine. Note: there are two grounds in this region, an engine to chassis ground cable, and the ECU to engine ground cable. See photo in above link.
The corroded ground connection allows a potential (voltage) to back feed the ECU inputs, which in turn damages the ECU circuits.

Some threads also suggest that the Alternator ground could be at fault, which can also cause a potential (voltage) to back feed the ECU inputs in some manner.

To repair your car, the following sequence seems to be suggested:
1) inspect and clean the alternator grounding bolt and connections
2) inspect and clean the ECU grounding wires under the airbox
3) alternate step; drive the "limp home" ECU equipped car to the dealer
4) replace the broken ECU with a new one
5) have the dealer reprogram the ECU via the OBDII port so the IMMOBILIZER and the ECU are synchronized ($89 fee at the dealer). (Also bring all of your keys fobs)
6) pray to the Honda gods for a few seconds, then start your engine
7) check to see if there are any fault codes... etc..

I will tell you how my repair goes...

HLNW
Nov 2012

Aetoc

iTrader: (1)

Not that it's a solution to this particular problem, but I solved mine by getting a new ECU. A bad pimary ground caused the alternator to fry the ECU, apparently someone common of an issue, so if you're experiencing the same issues I was, there's a probable solution.

Herman Wiegman

Here is an update on my 2002 Civic EX with manual transmission which exhibited the "limp home" mode and "clicking ECU relays" problem.
It has been repaired with a new ECU and all is looking good.

After the car developed the limp home mode and clicking CEL syndrome,
I was able to clean up the ECU ground on the engine, the engine to chassis ground straps, the battery to chassis to engine ground connections.
I then ordered a used ECU replacement through the dealer for $250 (who obtained it form a local junk yard).
Finally, the car was driven in limp mode to the dealer where I popped the used replacement ECU into the dash (behind the glove box), and the dealer reprogrammed the replacement ECU to the car's Immobilizer and keys (for $98).

Presto, everything working again.

Note: the alternator checked out as "good," and was able to recharge the battery at 14.5 volts (cold weather) even with all the lights and fans on, so I did not change it. I was shocked to see the price of a new Honda alternator was >$500, and a remanufactured one for >$350.
I did add an additional alternator to chassis ground wire to give an alternate current path around the mounting bolt.

It seems this ECU failure is somewhat rare and does not represent a significant number of occurances.


cheers,
HLNW

dem0nk1d

with my 2004 which im currently in the process of getting running correctly has issues communicate through the obdII port. i'm wondering if this could be a ground issue as well.

vitaminfeeder

Hi gys i am new here and have trouble with my 2004 civic lx two door car
It has a code P0134, O2 sensor no activity, bank one sensor one

I replaced the upstream oxygen sensor with new denso sensor the same one that the car had.
The check engine is still there shows the same code as i indicated above
no change happened when I put in a brand new oxygen sensor, it just behaves like nothing been done at all.

The car about 1,5 months ago suddenly shuddered and tried dying like the dashboard gauges all flashed their needles erratically and then everything came back normal again
about a week ago the car did absolutely the same thing again
also the idle is not always good the engine would idle just fine and then would shudder some like kind of losing it and again will come back to normal idle
it does this kind of thing all the time every 30 seconds to 2-3 minutes it would worsen the idle shudder somewhat and again smooth out

when i drive about sixty five or higher it would like lose power for a moment and again have it back which feels like slight jerking it can do it on some drives almost all the time and on some drives not at all

spark plugs are fine looking good NGK still have life to go.
good spark on all plugs

My suspicion is the ECU, but I would listen to experience and expertise gladly,
thank you for any input you can help with

vitaminfeeder

Hi gys i am new here and have trouble with my 2004 civic lx two door car
It has a code P0134, O2 sensor no activity, bank one sensor one

I replaced the upstream oxygen sensor with new denso sensor the same one that the car had.
The check engine is still there shows the same code as i indicated above
no change happened when I put in a brand new oxygen sensor, it just behaves like nothing been done at all.

The car about 1,5 months ago suddenly shuddered and tried dying like the dashboard gauges all flashed their needles erratically and then everything came back normal again
about a week ago the car did absolutely the same thing again
also the idle is not always good the engine would idle just fine and then would shudder some like kind of losing it and again will come back to normal idle
it does this kind of thing all the time every 30 seconds to 2-3 minutes it would worsen the idle shudder somewhat and again smooth out

when i drive about sixty five or higher it would like lose power for a moment and again have it back which feels like slight jerking it can do it on some drives almost all the time and on some drives not at all

spark plugs are fine looking good NGK still have life to go.
good spark on all plugs

My suspicion is the ECU, but I would listen to experience and expertise gladly,
thank you for any input you can help with

vitaminfeeder

sorry double post messed it up...