523i E61 LCI rough idle

[kaltoft]

Hello

I have been having some problems with my 523i E61 LCI recently.

I have been experiencing rough idle when the engine has warmed up for a while, and recently the yellow check engine light has appeared.
When the engine is cold, the idle is fine, after 10-15 minutes of driving, when the engine has warmed up, the idle becomes rough, as soon as the RPMs reach above about 1000 RPM the engine runs fine.

The current mileage of the car is about 107.000 miles (172.500 km)

The spark plugs were last changed at about 55.000 miles (88.000 km) so they are due for a replacement. I have ordered new spark plugs, and plan to change them as soon as they arrive.

I read out the error codes, and got the following:



The error codes: 2B07, 2B06, 2AFB, 30DA, 2A2B, 2A2C have been logged at about the same time as the check-engine light appeared.


2A2B:



2A2C:



2B07:



2AFB:



2B06:



30DA:


The spark plugs are due for a replacement, but if they were faulty, I would be able to see fault codes related to the cylinder that had ignition failures, right?

Any idea about what the issue could be ?

[gisela]

have u fix this?

[kaltoft]

have u fix this?

No. the problem is not fixed.

I have, however, taken some further steps.

I have read out som live sensor data from the car, i measured the following:
- NOx readings from NOx sensor
- Voltage from the 2x O2 sensors before cat.
- Exhaust temperature

All sensors reported plausible values except the NOx sensor. NOx kept being reported as '0 ppm'. Exhaust temperature read about 300C (575F). Voltage from O2 sensors varied with the RPMs of the engine

As of now, my intentions are to replace the NOx sensor and see if that fixes the problem.

If the NOx sensor breaks shortly after, I do believe I have a problem with my injectors, which I will then have to replace. They are quite expensive though, so I hope replacing the NOx sensor fixes the problem.