P0235 MAP sensor error

[BahnStormer77]

Hi - I know I've got an A6 snotwagon, but it's the S5 engine and drivetrain (3.0T supercharged), so there's a LOT more chance of getting a hit on this questions in an S4/S5 forum - forget about the sheer numbers of that engine in an A6, also far more S4/S5 enthusiasts than A6's!

Does anybody know the most likely causes + fix for this P0235 error. I just got a check engine light, scanned error codes with an ODB2 dongle (Torque Pro) and got this code.

Is it likely that the car needs a new MAP sensor or possibly just a case of unscrewing it and giving it a blast with some carb clearer?

Car is 9yrs old now, but only has 24k miles and has had regular Audi services every 1500-4000 miles (roughly every 12 months), the last one being a month ago - it is entirely stock, other than a Quantum remap that was done about 6 yrs ago and then re-applied about 12 months ago when Audi wiped it with and ECU flash.

 

[pelhamsdetailing]

Have you tried another app to scan your car? Torque Pro thinks my 3.0TDI swirl flap was a cam adjuster when I had issues with it. A quick google revealed the "P0235" code is related to turbo charger boost. There is a free app called Car Scanner that I use that has been more accurate with its understanding of fault codes, as well as better data recording.

Car Scanner ELM OBD2 – Apps on Google Play

Trip computer+car diagnostic tool with widest variety of features and dashboard!

play.google.com

Give that a try, scan your ECU, and maybe even do some specified vs actual for the charge air.

 

[BahnStormer77]

thanks for the feedback, car is supercharged... it is remapped, so it holds boost for longer (higher into the rev range), but it was like that for well over 5 yrs with no errors... I'm pretty certain that it is due to a faulty sensor.

 

[BahnStormer77]

I'm hoping this one is on the right track:

Some tips here........ https://www.audizine.com/forum/showthread.php/845241-Reoccurring-P0235-and-P0068?highlight=P0235

So I'm buying some of this: "Wynns WY29881 Petrol EGR Cleaner" - it says for cleaning the "air intake system, air flow sensors, inlet valves and EGR system" - so pretty much rebadged TB cleaner, but maybe less likely to have anything that would corrode sensors

 

[BahnStormer77]

Okay... I think I fixed this two weeks ago... read on if you want as I'm not certain if I'm FULLY out of the woods.

I took off the two little "plastic" rails on either side of the engine (2x Torq, T27 IIRC).... and removed the two inlet manifold sensors on either side (2x Torq T30 IIRC).

The sensor needs to be eased out (small amount of twisting side-to-side, pulling in the straight line, minimal tipping) - it looked pretty sturdy, but apparently they can be snapped.

I just unclipped the sensor and moved it away from the car and gave each one a liberal blast with the "EGR Cleaner" (removing the earwax-like "gunk" you see in the photo above).

Re-assembled exactly in reverse of the original.

Difficulty rating 2/10
Duration I took about 30min, but I was flying blind, dropped the Torq bit into the engine bar twice, etc, etc... I could re-do it in 10min now.

After that, I rushed out.... took the car for a quick blast and was able to regenerate the error with 100% accuracy

I went and sulked, plotting if I should:
a) wait for the engine to cool down and then attack the MAP sensor - same style, but but RIGHT down the back of the engine, under a seriously messy looking little box of vacuum hoses.
or
b) re-do the inlet manifold sensors, but soak them more.

Either way, it is irrelevant. I decided to go and play some computer games and blow stuff up instead.... then took the car out for a drive a week later and it SEEMED fine.... I think I managed 3-4 high-rev pulls and no sign of the error!!

Another week later, a 200 mile family road trip.... and it really WAS fine!!! Lots of fast A-road, foot-flat roundabout exits.... deep into the red-line in each of the lower gears and it was pulling like a steam train... was "Making Good Progress" and no sign of the error at all!!

The only casualties are a missus that thinks I'm a lunatic and excessive consumption of fairly expensive high octant petrol! (both of which are par for the course)

 

[BahnStormer77]

error seemed to come back after a few months

 

[pelhamsdetailing]

I'd be interested to know if the seal is doing its job sufficiently and not letting in weird gunk again. Maybe another unplug and check, as well as a general wiring health check from point A to B as best as you can. The next step is potentially a replacement one, as it may just simply be almost there on life span regardless.

 

[BahnStormer77]

Wiring certainly looked fine at the top, but I'll trace it down to make sure there's nothing obvious damaged.

I'm also going down the thought process of it possibly needing new sensors: low mileage, but it is 11yrs old, so it could just be corrosion over time?

I still have plenty of the cleaner, so I'll give them a good blast + soak when I get them out to check the part numbers.

Has anybody tried the sensor around the back of the engine too? Is it likely to also need cleaning and/or replacing? I think I'll need one of the Ryobi right-angle Torx drivers to get to that one around the back (engine top Torx are straight in with a screw-driver ).

 

[Zac101]

I have had the same issue on my car for over a year now on my S5, comes on when it wants to. Can be 6 months or could be 2 weeks has a mind of its own! I clear the error with a code reader and works for a while then like I said comes on 2 weeks later or 4 months.

I’ve had 2 different sensors changed one being a MAP sensor, only put good fuel in. I’m also curious to know how to fix it. Thinking of taking it to audi as independent garages don’t know what it is.

mine comes on after coming off a roundabout and slowly accelerating, it holds the gear longer than it should and then the light comes on.