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Error Code 45 - Map Sensor. HELP!!??

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Hi All,

firstly please let me apologise if this is in the wrong section l, it's my first post.

Im having a problem that I cannot seem to cure, I keep getting a CEL every time I cold start the engine that goes out after about 5 minutes, it doesn't come on once the engine is warm, so I connected the read cables under the dash to find code 45, I changed the map sensor and the pressure exchange solenoid valve that sits below it and still the problem persists, if anyone can enlighten me as to why this is happening I would really appreciate it

Thanks Guys!


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Hi n welcome , what model is it and has it been mapped or modded?

It could be a air leak between maf and map sensor . As this would make the ecu see a difference in the air measured between the air filter and inlet manifold.

Although I would expect that to show up more under boost than cold idle. It might be worth a visual check for perished vac lines and cracks in the intake and tmic y pipe .

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Hi, I appreciate your quick reply!!

its not mapped and currently the only "mods" it has is a silicone intake hose if you would call that a mod😂 And a HKS VTA BOV, other than that it has a standard intercooler and standard air box minus the resonator in the wing, I will check for vacuum leaks and would intercooler leaks cause the map sensor to see more air? 

thanks for your help!!


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No problem ,bud .

A leak Anywhere between maf and where the inlet manifold connects to the heads , could show up a maf or map code .

It could be the new intake pipe allowing more air in than the stock one . As someone fitted a new intake pipe to their newage sti and although it ran fine, after 2 days they had a eml light come on at start up .

It's now been remapped and the light has not come back on but classics do tend to be a bit more forgiving when it comes to minor breathing mods .

Hope you suss it and keep us posted [emoji106]

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Hi Mate,

the problem seems to have moved from when the car is started to when I drive, seconds later it goes out, the error code is still 45 which says to me that maybe the wiring is faulty but as I say it only seems to come on when I hit a slight bump in the road, this problem is driving me mad!! I can't see any vacuum leaks around the tubes or anything so I think the issue could be wiring, and why it came on at start up could be because the wiring was not sitting right until I hit a bump in the road.

cheers for your help!


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