MY2005 D5 boost pressure problem

[exdirectory]

I am a basic diyer... appreciate some guidance!

Have a PO236 code, turbo sensor A circuit, I removed the turbo control valve and gave that a good clean but to no avail and now realise I probably should have removed the boost pressure sensor for a clean... but I can’t find it!

Could I get some pointers how to find please?

Was keen to at least explore for any problems before hitting the main dealer!

[gmonag]

Generic OBDII codes can be misleading in the XC90. Only code readers that will read Volvo codes will give accurate DTCs - VIDA/DiCE being the best option.

The MAP sensor is on the back of the intercooler where the air charge pipe comes out.

I suspect your problem is not the sensor at all but a real boost pressure issue. In a MY2005 the turbo is controlled by vacuum, so any leaks in the vacuum system can produce this issue (tubing, brake servo, engine mounts, turbo IGV actuator). The turbo controls output by use of variable inlet guide vanes. These are prone to sticking/coking up and results in overboosting.

You have a lot to test/diagnose.

[exdirectory]

Found the MAP sensor, thanks for that, easy removal once you remove the headlight. Took it out, cleaned it up with brake cleaner, put it back...

When I start the car if i take it to > 1000 revs no engine light, can sit there for while quite happily, as soon as I go to less than 1000 revs, 5 seconds later "engine service required" comes up and then stays on until next ignition start.

Agree, vida etc is way to go but was hoping to save myself some money, boost sensor is £40, a new TCV is £60.

Walking into volvo main dealer they will charge me £200 just to step in to their hallowed reception!

Was tempted to try one of those parts first. Any thoughts?

[gmonag]

Don't fire the parts cannon. Test, diagnose, then swap parts. I've given you lots to look at.

[paddy74]

You do realise, that all you need for a proper diagnosis is a DICE (=the hardware), that you can get here at the forum for around £90 (or untested for the same on eB**) and a Laptop (if you do have one, that's fine). VIDA (=the software) is available around the Internet, if you look closely on swedespeed, you'll find it there either.

Maybe you can get VIDA together with the DICE... Checkout the "for sale" section in the V70 forum or ask @cheshired5.

[exdirectory]

I did not realise that, will consider, thanks

[exdirectory]

Quick question, I can't get to the dealer for a few days, am I doing any harm to the engine driving it around with this PO236 error?

[paddy74]

I'd say yes. If the car goes in limp mode, I wouldn't drive it further...

Chances are high, you are going to ruin something. In the end, this may be a lot more expensive.

The thing is, without knowing, what really is behind this generic error code, it is just guessing (maybe a ver expensive guess, maybe not...).

I'm sorry for yesterday, I always assume that VIDA is common knowledge... I'm writing a small FAQ right now, I'll upload it later today. Hope this helps.

[exdirectory]

Reporting back...

In the end I had a good look around the engine bay and could not see any signs of leaks so just decided to swap the boost pressure sensor and take the risk since it was an easy swap (just remove the near side headlight (in UK) and it is underneath - need a torx screwdriver, takes about 5 mins.

Engine light went away instantly.

Hoorah, one of my few successes when it comes to engines!

Cost me £40 for the part from ebay. Part was new and looked identical to the one I removed.

[gmonag]

Great result.