Peugeot 308 check engine light question

[nedim0702]

Since I had some issues with my 2012 Peugeot 308 RNEG unit, I've taken it out and sent it for repair. After taking the unit out, and driving without it for a couple of minutes, a check engine light appeared.
I've not noticed any changes in driving, and everything seems to be working fine (engine-related).

I wondered if the check engine light is connected to the RNEG radio unit now missing from the car. Has anybody experienced anything similar to this?
Sadly I haven't got any kind of diagnostic tools to read the code. Secretly hoping that it might be connected since I have a 1-day family trip planned tomorrow (around 450km in driving distance), and now I am wondering if I should cancel that until the CEL is checked out.

Thanks in advance!

[GiveMeABreak]

Very unlikely it is connected to the RNEG, as EMLs are usually concerned with the engine management or emissions but without a diagnostic and a fault code, we won't know what it is.

[nedim0702]

Thanks Mark! I’ll schedule an appointment with my mechanic to check it out.

[cit-rotti]

This may be related to the removal of the telematics unit.

When I remove the RNEG 2 from my Citroen C5X7/HDI 163/2013, the engine control light also lights up because the engine control unit is no longer informed about data supplied by the RNEG 2.

There are no performance problems.

After installing and connecting the telematics unit, everything is fine again.

Greetings Wolfgang

[GiveMeABreak]

He may have the earlier RNEG, not the RNEG2, but there's no direct connection to the engine ECU on these, only the BSI

[nedim0702]

An update to this:
I've had a friend of mine read out the codes, as he has a Diagbox, and two faults came out:
U1118
P2297

I cleared the codes, both codes appeared again after 10 minutes of driving.
Looking through the forum, the U1181 might be connected to the RNEG unit being non-existent at the moment, and the P2297 might be due to a bad O2 sensor, probably on DPF? Not sure about either, I would love more info on these!
Thanks

[GiveMeABreak]

U1118 can refer to any system! This fault code is a communications / data fault and can appear under 20 plus different systems, so we need to know the context under which it comes up, Usually the U*** fault will be listed against the specific system when using the diagnostics, so we know which system it is applicable to.

Fault Code:	P2297
Description of Fault:	Measurement of the concentration of oxygen: Concentration not plausible with the pedal released. The concentration of oxygen measured is 4 % higher than the concentration of oxygen calculated during the pedal release phase (The fault appears after 2 seconds) Conditions of activation of the diagnostics: The following conditions have to be met: - Engine running - In the pedal release phase
Conditions for Fault to clear:	Ignition switched on
Downgrade Modes whilst Fault is active:	-
Symptoms:	Slightly higher fuel consumption
Suspect Areas:	Oxygen sensor Electrical harnesses Connectors

[nedim0702]

Thanks Marc! I'll see what's up with the O2 sensor, but I can live with higher fuel consumption for the time being, until I have a chance of looking at that. (on a side note, coming from a VW 1.8TSI engine, the HDi fuel consumption is next to nothing compared to it lol)

As for the U1118 - totally understand! Sadly, my friend and I were both amateurs and didn't bother to look at what the U1118 code was listed against. I'll try and re-read the codes once the RNEG unit is returned from the repair.
Reading through the old posts on this forum, I've found one of the "Downgrade Modes" of the U1118 is "deactivation of the vehicle cruise control", which I have had happen several times, and for no apparent reason (cases where I was cruising at 70kmh with CC on, then merging on the highway and being unable to set CC at 130kmh with three dashes blinking).

Always thought that either I was using the CC wrong or that might be a break pressure switch problem but never got around to it.
One question - after reinstalling the RNEG unit, should I do the BSI reset procedure? Will that reset the U1118 code? Or even both?

Thanks!

[GiveMeABreak]

The engine management ECU will deactivate cruise control as a safety feature if it detects any problem with the air or fuel system or any other system like the ABS as necessary.

So I would get your RNEG back in and make sure you first use the BSI Reset / Battery Disconnect / Reconnect Procedure to disconnect and later reconnect the battery to ensure there are no electrical glitches.

Once you've done that, run a diagnostic to see if there are any other faults.

[nedim0702]

The funny thing is that the cruise issue happened before any warning lights had been displayed. It seems to be working just fine now with the EML light on. Alas, I have a feeling that it might be a pain to chase down that issue without a Diagbox or live data while driving.
And thanks for linking the BSI reset procedure, I'll be sure to follow it down to a letter.

[GiveMeABreak]

So you won't get a specific EML for cruise control as it's not the cruise control that's necessarily at fault. It will either just deactivate or will refuse to set a speed or resume, with the dashes displayed.

This means that the engine ECU has disabled it because an engine problem has been detected at that time. The cause of the fault may ne intermittent or temporary under certain diving conditions. Often restarting the vehicle will reset the CC - but as soon as the fault is triggered again, the same thing will happen.

So yest it needs a diagnostic to see which actual fault codes are being triggered which should be stored in memory if not currently active.

When you get those, put them up here with your VIN for additional help.