OBD2 Codes P1123 & P1125

[Richard Hamilton]

Maybe I should try this as a new post. My DME fault register shows P1123 and P1125 fault codes, but I DO NOT get the CEL coming on at all. The car runs fine, but I would like to find out what is wrong sooner, rather than later. The DME actual values I am reading are:

Idle Speed - 680rpm

Load Signal - 1.3ms

Mass Air Flow - 19 kg/hr

Hot film mass air flow meter - 1.31 volts

Engine Temperature - 90°C

Throttle Plate Angle - 0°

Ignition Timing - 5.3° crank

Specific Air Mass - 17.0 kg/hr

Specific Air Adaption - 3.0kg/hr

Injection Time - 2.8ms

Oil Temperature - 90°C

IATS - 27°C

ECTS - 92.3°C

Oxygen Sensing Cyls 1-3 - 0.9 to 1.0 (varying)

Oxygen Sensing Cyls 4-6 - 1.0 to 1.15 (varying)

Range cylinder 1-3 (FRA) - 1.02

Range cylinder 4-6 (FRA2) - 1.01

Range cylinder 1-3 (TRA) - -0.36

Range cylinder 4-6 (TRA2) - -0.33

O2 sensor ahead of cat conv (1-3) - 0.1 to 0.7 volts (varying)

O2 sensor ahead of cat conv (4-6) - 0.1 to 0.7 volts (varying)

Camshaft Position deviation - -3.0° crank

Rough running threshold - 8.4

Rough running - 0.0

Segment (A) - 1.0

Segment (B) - 1.0 This should be Segment B - I can't get rid of the smiley!

Learning progress, sensor wheel adaption - 0.000

Misfire detection - 0.000

Engine compartment temperature - 60.0°C

Oxygen sensor heat resistance ahead of cat conv - 3.2ohms

I have checked the fuel pressure, and it is spot on - 3.8 bar engine off, and 3.3 bar at idle. I think all the readings are within the range of nominal values in the manual, except the TRA values that are way out.

"TRA - Time Relative Adaptation; a fuel injection adaptation method used to compensate for engine/sensor changes at idle, which are short term & small affecting the AFR, e.g. intake air leaks, and which generally varies equally with +/-values under normal conditions (taken from www.systemsc.com/glossary.htm)". I don't think it is an air leak, because the idle speed and mass air flow are within limits. The MAF sensor readings also seem to be correct, and I think the FRA values being correct bear this out.

Any ideas anyone?, and BTW what is the EVAP canister purge valve mentioned in other similar posts? Sorry for the amount of data, but I thought that too much was better than too little. I'm not sure what all these readings mean - I just took them straight off the PST2.

Edited January 23, 2005 by Richard Hamilton

[Tool Pants]

This has generally been expained to me several times but it just seems to go in one ear and out the other.

You can have a pending fault code but no check engine light. If the fault is detected again then the light comes on. Something like that.

The other thing is that you are in the UK and the US OBDII system is different than yours, as is your emission system. There is actually a European OBD message board but I cannot find the link.

[Richard Hamilton]

Thanks Jeff

I guess I should stop worrying until it starts to run rough.

Can you tell me what the EVAP canister purge valve is?

[Loren]

On a US Carrera it looks like this: