2011 2.0 163Hp C5 Engine Management Light On;- Fault P0235

[PGrehan]

I had the engine check light on the instrument panel light up on Thursday morning, and has not gone out since.

I've driven it about 150 miles since and it seems to be driving as normal despite this.

I bought a basic EOBD code reader which indicates fault code p0235 (Turbocharger Boost Sensor A Circuit Malfunction).

I'm not sure where this sensor is in the engine bay. I'd be grateful if anyone familiar with this could describe where to find it.

From what I can find on the net, root cause is likely to be split tubing feeding pressure signal to sensor, faulty sensor itself or faulty wiring to sensor. Has anyone on this forum experienced similar issue, and if so what was the route cause in that case?

 

Thanks in advance.

[TheJudge2009]

Maybe the link below can put you in the right direction...

 

http://www.citroen-owners-club.co.uk/citroen/topic/15557-p0235-please-help-citroen-c5-22hdi/

[paul.h]

The boost sensor is probably the MAP sensor (manifold pressure) Citroen part 1920QR http://www.ebay.co.uk/itm/NEW-GENUINE-CITROEN-PEUGEOT-ENGINE-MANIFOLD-PRESSURE-MAP-SENSOR-1920QR/382021182362?_trksid=p2047675.c100623.m-1&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D43783%26meid%3D38e118fc3a5149d8a1bb93c9798e253f%26pid%3D100623%26rk%3D5%26rkt%3D6%26sd%3D361915212630 so will be on the inlet manifold on the left (as you look from the front) at the narrow bit before it widens. It also includes a temperature measurement. You should check if it is blocked and also its electrical connector as well as the wiring. If your code reader gives live data you could see what pressure it is giving to see if it is realistic but you should have atmospheric pressure without the engine running and then about 0.2 bar boost at about 2500 rpm with the car not moving but when moving at full load should be about 1.4 bar or about 1.1 bar if not moving. If your reader gives values in kPa, then atmospheric pressure is about 101 kPa, 0.2 bar about 120 kPa, 1.4 bar about 240 kPa, 1.1 bar 210 kPa - note that absolute pressures are being given in kPa whereas the boost pressure is gauge pressure.

[PGrehan]

To the Judge and Paul R,

thank you for your replies.

I've located the sensor part no 1920QR. I removed it to see if there was an obvious blockage, but there was not. I was surprised to see that the part of it that was inserted in the path of the intake airflow was coated with an oily film, but maybe that's normal. I guess that the exhaust gas recirc air could be the cause of this.

Anyway, unfortunately the code reader that I have is pretty basic, and only reads the codes. It will not display live data, so I can't do any further diagnosis. I decided to take a flyer and buy a replacement sensor 1920QR - hopefully the replacement will sort it out, but I won't know until later in the week or worst case next week.

 

I'll let you know what happens.

 

Thanks again.

[PGrehan]

I received part 1920QR and fitted it last night. The engine check light remained on.

I checked again this morning and the light remained on. I drove it about 25 miles, parked it up and when I returned shortly afterward and started her up, the engine check light remained off this time (apart from the normal few seconds lighting up at the start).

I've since had a few more starts and the light has remained off.

At this point it's looking like the problem is resolved.

Thanks to those who posted offering advise - it was very helpful.