Hi, looking for help, my car wont start, glow plug symbol flashing and thrown up some fault codes, p0642 p0408 p0341 p0236, was working perfectly no issues, then tried to start it and it just wouldn't start, rac couldn't start it either, they tried to say it might be the camshaft sensor but I ain't to sure as i think it's only popping up fault code because it won't start, anyone else had this problem and managed to fix it, thanks 

Doing some quick research, the common link with some of the codes is with the 5 volt reference not being at 5V.  

I am assuming that the 12v battery was checked by the RAC is OK?

I think battery was OK, I did jump start someone then problems did happen 

Did the RAC responder actually test the battery?

No he just checked the fuses on the battery, so best bet is to buy a new battery and see if that solves the issue 

It would be best to get the battery properly tested first before considering replacement.

Does the engine appear to crank at normal speed when it fails to start?

I'm concerned about your reference to jump-starting another vehicle before this issue first occurred, are you certain that you followed the correct procedure when you did this? 

Yes, engine was turning over perfectly, issue only started after I jump started a friend, it still turns over but just not starting and i have now made battery flat by keep trying, I have purchased a smart battery charger so I can charge and check it's condition and I have also purchased a new camshaft sensor to replace as that's one of the codes, if issue is still there after those to things then I am stumped because I really can't see it being anything else, checked all over the car and can't see any doggy wires or faulty connectors 

3 minutes ago, flipinsake said:

Yes, engine was turning over perfectly, issue only started after I jump started a friend, it still turns over but just not starting and i have now made battery flat by keep trying, I have purchased a smart battery charger so I can charge and check it's condition and I have also purchased a new camshaft sensor to replace as that's one of the codes, if issue is still there after those to things then I am stumped because I really can't see it being anything else, checked all over the car and can't see any doggy wires or faulty connectors 

Do you mean crankshaft position sensor? (rather than 'Camshaft') - this can apparently cause the issue of diesels cranking but failing to start - and seems fairly common. 

No the camshaft position sensor, it's next to the camshaft 

The codes in full are:

P0642 Sensor Reference Voltage A Circuit Low

P0408 Exhaust Gas Recirculation Sensor B Circuit High

P0341 Camshaft Position Sensor Circuit Range/Performance

P0236 Turbocharger Boost Sensor A Range/Performance

 

Unlike a faulty crankshaft sensor, a faulty camshaft position sensor doesn’t normally stop the engine from starting.

 

I would be concerned that if the engine doesn’t start with a fully charged battery that the ECU maybe unhappy after the jump start.

1 hour ago, ChrisTids said:

The codes in full are:

P0642 Sensor Reference Voltage A Circuit Low

P0408 Exhaust Gas Recirculation Sensor B Circuit High

P0341 Camshaft Position Sensor Circuit Range/Performance

P0236 Turbocharger Boost Sensor A Range/Performance

 

Unlike a faulty crankshaft sensor, a faulty camshaft position sensor doesn’t normally stop the engine from starting.

 

I would be concerned that if the engine doesn’t start with a fully charged battery that the ECU maybe unhappy after the jump start.

^^^^ + this - and there are a number of references on the forum to a failing crankshaft sensor not raising a fault code when engine fails to start. 

OK well I'll replace crankshaft sensor aswell, is there a voltage stabilizer module on a roomster or is it built into the ecu, thanks 

Update, yesterday the car just started working again all fault codes had gone and drove nicely, this morn when I went to car, the glow plug symbol was flashing again so I never started engine and i automatically checked for codes the only codes that popped up were p0642 and p0408, tried to start the car and it was turning over but refusing to start again, 

Edited 13 July, 20241 yr by flipinsake

I understand that the 5v is generated by the ECU, from your description it now sounds more like a damaged wire or connector 

I checked all connectors and I think it's the camshaft sensor connector, unplugged it and plugged back in and car started working again, I have a new sensor so if it plays up again, I'll just have to change the sensor which on my car is a nightmare because I have to take the camshaft pulley off