Hi,

Civic EX 2006 135k miles.

For the last 18 months its had a starting problem, sometimes it will start first time, other times it requires 4 or 5 attempts. It always starts, just has to be "coaxed"
Problem is the same hot or cold.
Shows no trouble codes.
Took it to large local Honda dealer, still no trouble codes.
They had it for a day and a half. Checked the battery, replaced earth straps and tested a whole bunch of sensors.
Even sent live data feed to Honda HQ in California, no progress.
Honda HQ says try replacing the ECU computer module. Had to take the car back before they tested with replacement ECU. They will test it when we can spare the car.

When I got the car back, the symptoms are the same as above but now it shows a CEL and will go into "limp" mode every now and then, refuses to rev above 3500.

My OBD software shows code P1129.

Any help appreciated.

 

To add to the post above, when I clear all codes, the P1129 code does not return.

 

P1129 - Downstream Heated O2 Sensors Swapped.

Possible causes
Crossed HO2S harness connectors (downstream).
Crossed HO2S wiring at the harness connectors (downstream).
Crossed HO2S wiring at the 104-pin harness connectors (downstream).

The heated oxygen sensor (HO2S) monitor determines if the HO2S signal response for a fuel shift corresponds to the correct engine bank. The test fails when a response from the HO2S being tested is not indicated.

 

[QUOTE=rekomstop209;782910]P1129 - Downstream Heated O2 Sensors Swapped.

When I look up P1129 it says "MAP Higher Than Expected".

Where do you get your info, link please.

 

[QUOTE=Straw Dog;782914]You are correct 1129 is Map higher than expected, did you get the pcm swapped?
is it a crank no start? or a no crank no start?
does your immobilizer light flash when when cranking, when the car does not start?
do you know if they check for immobilizer errors, all attempted starts get logged in Immobilizer data logs

 

[QUOTE=scrapdog2grand;783215][QUOTE=Straw Dog;782914]

You are correct 1129 is Map higher than expected, did you get the pcm swapped?

No we have been unable to spare the car due to heavy commitments

is it a crank no start? or a no crank no start?

It is crank, no start. Starts after 4-5 attempts.

does your immobilizer light flash when when cranking, when the car does not start?

I don't know, what does the immobilizer light look like.

do you know if they check for immobilizer errors, all attempted starts get logged in Immobilizer data logs.

I do not know but I will ask when we next get the car back to the dealership.

 

[QUOTE=Straw Dog;783224][QUOTE=scrapdog2grand;783215]the Immobilizer light look like a key(green) on the instrument cluster.
it should go out after a couple seconds, if it continues to flash while trying to start the engine, it is not reading the coded key properly.
not common with this year.

did the check engine light ever come back on after being cleared?
I have seen hard starts and the p1129 caused by a bug or debris getting caught on the hot wire of the mass airflow sensor.

 

[QUOTE=scrapdog2grand;783267][QUOTE=Straw Dog;783224]The immobilizer light comes on briefly when I turn on the ignition, but goes out almost immediately I start cranking. Does not come on again..

As far as debris on the MAF hot wire I will need time to check that.

Thanks for your continued input.

 

[QUOTE=Straw Dog;783273][QUOTE=scrapdog2grand;783267]Have cleaned MAF but makes no difference. Have also tried running with MAF disconnected, makes no difference.