Technical Map Sensor/Boost Pressure sensor.

[Manic mechanic]

I have the code P0235 and MIL on, 2004 Doblo 1.9 JTD Diesel. It sems I may have an issue with the Map sensor but there seems to be confusion online as to whether there are 2 sensors (Map and /or Boost Pressure) or just one. Been reading some generic stuff online and I believe it's a common issue, some cars have one and some two. I have found the MAP sensor OK, so I could do with knowing if that's the area I need to check in or if there is another sensor and if so where is it?
I have a cheap code scanner which I have had for about 6 years, this is the first time it has ever came up with a code for anything, hence my hesitation believing it, so it's P0235 and it says "Current stored Turbo/Supercharger boost sensor A, Circuit wiring Map sensor T/C SC boost pressure sensor". I don't see any problems with the wiring so wondering if it's worth just changing the sensor. No other codes, car runs fine but it is a bit smokey (white/Blue), not all the time but kind of on and off. First thing I did was run an injector cleaner chemical through it but it hasn't helped. Appreciace any advice you can offer, Thanks.

 

[bugsymike]

I have the code P0235 and MIL on, 2004 Doblo 1.9 JTD Diesel. It sems I may have an issue with the Map sensor but there seems to be confusion online as to whether there are 2 sensors (Map and /or Boost Pressure) or just one. Been reading some generic stuff online and I believe it's a common issue, some cars have one and some two. I have found the MAP sensor OK, so I could do with knowing if that's the area I need to check in or if there is another sensor and if so where is it?
I have a cheap code scanner which I have had for about 6 years, this is the first time it has ever came up with a code for anything, hence my hesitation believing it, so it's P0235 and it says "Current stored Turbo/Supercharger boost sensor A, Circuit wiring Map sensor T/C SC boost pressure sensor". I don't see any problems with the wiring so wondering if it's worth just changing the sensor. No other codes, car runs fine but it is a bit smokey (white/Blue), not all the time but kind of on and off. First thing I did was run an injector cleaner chemical through it but it hasn't helped. Appreciace any advice you can offer, Thanks.

Don't know if any help , but many years ago I bought a high mileage 05 Doblo 1.9 JTD with tonnes of black smoke, I tried a MAF sensor which has five terminals just after the air cleaner and reads airflow temp as well, nothing seemed to cure it but in the end I found it was the wiring plug that goes into the sensor and rewired the last few inches of the loom to it and problem solved.
However in your case you say (white/ blue smoke) so may be a different issue.
Possibly EGR related, some use an EGR blank on older engines.

 

[Manic mechanic]

I had another go with it again today, it seems I can't even cancel the code any more, so maybe it's got a bit worse The code does seem to indicate it's a Turbo Boost sensor problem but that may mean just something in the circuit isn't right or the sensor is giving wrong readings.
I have found sensors on E.Bay and they are not ridiculously expensive. I tried to photograph it today, that was a bit tricky managed to see it is a Bosch, so that should help in my search, a part number would have been nice but i was going to lose my friend's phone down th back of the engine and decide to cut my losses.
I also saw a You Tube video last nigh on how to test a MAP Sensor with a digital multi meter and guess what, my multi meter has been lost for 4 years and I just found it yesterday, so that's another thing I can maybe do. Just wish it wasn't so bloody cold outside, might feel more motivated.

 

[bugsymike]

I had another go with it again today,it seems I can't even cancel the code any more, so maybe it's got a but worse The code does seem to indicate it's a TUrbo Boost sensor problem but that may mean just something in the circuit isn't right or the sensor is giving wrong readings. I have found sensors on E.Bay and they are not ridiculously expensive. I tried to photograph it today, that was a bit tricky managed to see it is a Bosch.

I have made a similar mistake myself , chasing faults by fitting parts in the past, even recently I wasted hours trying to find why a Doblo 1.6 multijet was chucking out black smoke, in the end I invested in two hours labour by a diagnostic specialist and it was a small gasket leak at the egr pipe to the inlet manifold causing reduced boost and so black smoke, it already had a new turbo due to an oil leak, I had pressure tested the inlet side and located a few leaking hose clips , but if I had tried a smoke detector which I could have borrowed from a friend , I could have located the fault.
One of the codes showing on this was a MAP sensor error which may have been a guide if I wasn't so old school.

 

[Manic mechanic]

I bought a new sensor, fitted it, smoke disappeared, managed to cancel teh code and it seemed fine, for abiut a day then the light came on again. Different code this time for the Camshaft position sensor, so I cancelled that and 2 days later it's still OK. I think it's just a bit smoky when cold but here's what worries me. If the camshaft is in some way out of position, that may give me a fault code like that and if it is out of position it's not goig to be able to fire the fuel like it should, hence smoke. Which then all points to a problem in the camshaft/timing belt area, maybe a fault temsioner or similar. Am I going too far over the top with my theories or could I be right, maybe need to check the belt, tensioner, pulleys etc, certainly if the light comes back on. One thing I don't get is the correlation between the 2 codes, anyone any ideas?

 

[bugsymike]

I bought a new sensor, fitted it, smoke disappeared, managed to cancel teh code and it seemed fine, for abiut a day then the light came on again. Different code this time for the Camshaft position sensor, so I cancelled that and 2 days later it's still OK. I think it's just a bit smoky when cold but here's what worries me. If the camshaft is in some way out of position, that may give me a fault code like that and if it is out of position it's not goig to be able to fire the fuel like it should, hence smoke. Which then all points to a problem in the camshaft/timing belt area, maybe a fault temsioner or similar. Am I going too far over the top with my theories or could I be right, maybe need to check the belt, tensioner, pulleys etc, certainly if the light comes back on. One thing I don't get is the correlation between the 2 codes, anyone any ideas?

Don't think any direct correlation between the two codes.
If cam belt hasn't been replaced in the last few years /miles it is always a good idea to check it.
Recommended interval for replacement is 72000 miles or five years which ever comes soonest. It is an "interference" engine, meaning if belt breaks or is mistimed it damages the engine, as in valves meet pistons etc!
However I can't see if vehicle goes alright most of the time that cam timing would fluctuate, so maybe over thinking that area.
Is it possible when working on the Maf sensor area you disturbed the other sensor/wiring?

 

[Manic mechanic]

Thanks for the reply, 'Over thinking' you could be correct. I had teh battery dosconnected when I was working on it but I did unplug a few things just for access. There was another similar plug, could that be the Camshaft sensor? In which case that could be it but surely it shouldn't have happened if the battery wasn't connected? Timing belt was done about a year ago, before our ownership, so unknown mechanic/Garage.
We had the van out yesterday, same person driving as when the light came on but it was fine yesterday, not that it could be his driving but you never know

 

[bugsymike]

Thanks for the reply, 'Over thinking' you could be correct. I had teh battery dosconnected when I was working on it but I did unplug a few things just for access. There was another similar plug, could that be the Camshaft sensor? In which case that could be it but surely it shouldn't have happened if the battery wasn't connected? Timing belt was done about a year ago, before our ownership, so unknown mechanic/Garage.
We had the van out yesterday, same person driving as when the light came on but it was fine yesterday, not that it could be his driving but you never know

Safe while battery disconnected , I was thinking more if a wire got damaged or a connector wasn't a good fit when replaced.
If vehicle has run over a year since cambelt replaced I would say unlikely to be the problem. More likely in the first 500 miles.

 

[Manic mechanic]

Ok, I see what you mean, nothing damaged during the job though, I am usually careful. Just need to keep driving and see if anything pops up I guess.