1.6 HDI Intermittent Fuel High Pressure Exceeded & engine cuts out

**VTS_Tibi** · 15th May, 2016, 04:19 PM

Hi Guys,

I have a 2009 Citroen C2 1.6HDI 9HZ 110hp and once every month the fuel rail pressure all of a sudden gets really high, then the ECU logs P1166 and shuts the engine... Lexia says it's the "fuel pressure exceeded upper limit"

This is the PSA description for this fault code, which matches what I expereience with the car.:

When I managed to have a cheap BT ELM327 connected when the car did this fault, the rail pressure went really high and then after a few secs the engine cut out. This is not just what the fuel rail pressure sensor measures as the engine also gives out a very strong audible noise when this happens - so it confirms that the rail pressure is indeed too high.

I have already replaced the pressure regulator valve on the top of the fuel pump with a new one, replaced the fuel filter with a genuine one - these made no difference, the fault still happens, but as I written above only once or twice a month.

Could an intermittent short / open circuit cause this problem? I am thinking that something might happen making it open circuit for a few secsonds, and that would mean no control on the regulator valve, hence the pressure becoming really high.

Thanks,

Tibi

**VTS_Tibi** · 15th May, 2016, 04:32 PM

Just to add to this, the infodiag below states, that the fuel flow regulator of the Bosch CP1H high pressure pump which this car has is is normally closed.

http://service.citroen.com/dtt/IFD/A...nfodiag409.pdf

So if there is an open circuit, or if I disconnect the plug from the flow regulator the pressure would go up to the max (as it would not be regulated).

(this is exactly the opposite of the Bosch CP3.2 where it is normally open, so if you disconnect it it gives you 30-40bar rail pressure)

**smokey08** · 15th May, 2016, 10:33 PM

Was there any gunge on the old control valve when you removed it from the pump?

**VTS_Tibi** · 16th May, 2016, 08:24 AM

Sorry do you mean metallic swarf? In that case the answer is no, the valve was clear from debris and I also cut the fuel filter apart and there was nothing there. It was clean.

In case you are asking about sticky residue, then the tip of the valve (especially around the seal) was slightly covered in something which looked like silicone grease.

**synkrotronic** · 21st May, 2016, 09:13 AM

Hi,try to change connectors from fuel pressure sensor and regulator plugs,maybe a bad contact could do this.
If wrong information of sensor pressure on ecu,could change injection values

**noka** · 22nd May, 2016, 10:56 PM

bad contact on fuel preasure senzor,only clean conector with electronic spray

**dimitar** · 24th May, 2016, 07:10 AM

Just change the fuel pressure regulator

**Meat-Head** · 1st June, 2016, 10:01 PM

If had regulator & once a month

1) aftermarjet hid lights?

2) ecu

3) none of above

**VTS_Tibi** · 21st October, 2017, 10:16 AM

To update this thread in case anyone else will have the same issue in the future with the 1.6 HDI. Believe it or not, it was the BSM. There was a TSB from Citroen which referenced the DTC I had and the TSB stated the BSMs have a manufacturing issue.

The old BSM had a couple of relays which turned black (looked like from smoke or somethign similar).

I fitted a new BSM and the car has been fine since (this was a good few months ago).

**Meat-Head** · 21st October, 2017, 11:13 AM

ON TOPIC:- AND OFF TOPIC:-

once in a while you come across 307 perrol, not start, no fault codes, everything looks good on live data.

the bsm has "two" relays, one goes to feed coils etc the other feeds ecu, the relay gives out and no power to coils

ON TOPIC:-

so yours is in effect doing the same, put up with it would one day be non start.

**VTS_Tibi** · 5th November, 2017, 12:22 AM

Originally Posted by Meat-Head

ON TOPIC:- AND OFF TOPIC:-

once in a while you come across 307 perrol, not start, no fault codes, everything looks good on live data.

the bsm has "two" relays, one goes to feed coils etc the other feeds ecu, the relay gives out and no power to coils

ON TOPIC:-

so yours is in effect doing the same, put up with it would one day be non start.

Correct. Seen that happening on many C4s and just a handful of 307s, but mostly they were petrols.

Apparently on the 1.4 and 1.6 HDIs at around 2009 there was a change in the BSI (mine was a very late C2, which actually was more of a DS3 under the skin. All the part numbers were DS3 for the BSI, BSM etc..) and this issue affected the DS3, C2 and 207.