Check Engine Light

[superstar_tradesman]

The check engine light came on in my car today for about 30 seconds then went back out. I had just jetwashed the car, the engine was warm and i was driving off boost taking it easy as i pulled out from the petrol station.

It's a V3 STI 555 with 58k on the clock. Standard apart from a dump valve and H&S backbox. It made 254bhp on the rollers at Hypertech and all readings ie AFR etc were ok.

[superstar_tradesman]

any ideas anyone?

[the squiggle]

Probably pulled some water in the filter and gave the MAF a wash

[superstar_tradesman]

  The Squiggle said:

Probably pulled some water in the filter and gave the MAF a wash

Is that likely to cause problems with the MAF

[the squiggle]

  superstar_tradesman said:

Is that likely to cause problems with the MAF

Yup

Water will cause the signal from the MAF to go loopy temperarily and the ECU throws a CEL. The CEL goes out once the excess water has been removed from the MAF by general engine running and everything goes back to normal. You could reset the ECU to clear any codes if the car feels sluggish

[superstar_tradesman]

  The Squiggle said:

Yup

Water will cause the signal from the MAF to go loopy temperarily and the ECU throws a CEL. The CEL goes out once the excess water has been removed from the MAF by general engine running and everything goes back to normal. You could reset the ECU to clear any codes if the car feels sluggish

cheers mate the light has not been on since and the car is running fine.

[david_taylor]

  superstar_tradesman said:

cheers mate the light has not been on since and the car is running fine.

Think I mighy have been behind you today in Stenny. Were you heading towards carronshore at around 10-11?

[superstar_tradesman]

  dtabbit77 said:

Think I mighy have been behind you today in Stenny. Were you heading towards carronshore at around 10-11?

no mate it wasn't me.

[iain01]

My cel light came on last week, I had just fueled the car then stopped off at a shop, the car was warmed up and I gave it blast in second gear (6000rpm) after I left the shop and the light came on, took it back to dealer and they said it was throwing up an o2 sensor fault. They reset it and no problems since. The dealer told me it can be a common fault when you fill the car up fully, never happened on my wrx so I will wait and see incase its a faulty sensor.

[crispyduck]

  iain01 said:

My cel light came on last week, I had just fueled the car then stopped off at a shop, the car was warmed up and I gave it blast in second gear (6000rpm) after I left the shop and the light came on, took it back to dealer and they said it was throwing up an o2 sensor fault. They reset it and no problems since. The dealer told me it can be a common fault when you fill the car up fully, never happened on my wrx so I will wait and see incase its a faulty sensor.

iain, recommend you change dealers if they are giving you that advice. What mods have you got?

[iain01]

  crispyduck said:

iain, recommend you change dealers if they are giving you that advice. What mods have you got?

None at the moment, Standard GB270

[thefastone]

Take it that it was Kev at T&C that you spoke to was it? Kev does actually know what he's talking about, I would be inclined to believe what he's saying like... does sound odd kind like...

[superstar_tradesman]

Right folks the CEL came on again for about 30 secs then went off again. Car was warm it had been sitting outside my mates for about 10 mins, when i started the car and went to drive off the CEL was on, drove gently up the street an the light went off. any ideas how to find the fault , ie confirm it is the MAF and how much it's going to cost.

[fiestajohn]

Manually Reading ECU Codes

http://www.scoobypedia.co.uk/index.php/Kno...ReadingECUCodes

Impreza Fault Codes

http://www.scoobypedia.co.uk/index.php/Kno...CodeDefinitions

[superstar_tradesman]

Do you have to remove the cowling around the steering column to get at the connectors to manually read the fault codes?

[superstar_tradesman]

right troops, I just did a manual read of fault codes and it's throwing up code 23, the dreaded MAF.

Anyone know the best place to source a replacement

[frank c]

http://www.gradea-subaru.co.uk/3.html

I've had a wee look and this is the only one I've came across so far. Don't know what the company is like either but hth's.

[superstar_tradesman]

cheers frank i'll give them a bell after the holidays.

[the squiggle]

Version 3 MAF can be cleaned with brake cleaner

Good chance of blowing some contaminants through the filter onto the MAF during the jet wash

[superstar_tradesman]

  The Squiggle said:

Version 3 MAF can be cleaned with brake cleaner

Good chance of blowing some contaminants through the filter onto the MAF during the jet wash

Is this wise to try cleaning or am i better just getting a new one?

[nanaki]

well considering the cost of a new one i'd be inclined to try cleaning it. if it is broke you can't really brake it much more however if it works then you win!

[superstar_tradesman]

I'm going to give it a good clean tomorrow.

  Nanaki said:

well considering the cost of a new one i'd be inclined to try cleaning it. if it is broke you can't really brake it much more however if it works then you win!

[S T U]

Mines doing exactly the same, I'll be cleaning mine tomorrow as well I think. Also dies on the dualler in 5th when you put your foot to the floor to overtake. then picks up then dies then picks up then dies you get the picture.

[crispyduck]

To be honest, that sounds more like 'fuel cut' to me mate - over boosting in the cold weather causing ECU to cut fuel until boost drops, then repeats...

  S T U said:

Mines doing exactly the same, I'll be cleaning mine tomorrow as well I think. Also dies on the dualler in 5th when you put your foot to the floor to overtake. then picks up then dies then picks up then dies you get the picture.

[superstar_tradesman]

Mine hasn't done that mate, light only on for a few seconds then goes off, no loss of performance.

I would do a manual check of codes of the ecu and find out what the problem is mate.

  S T U said:

Mines doing exactly the same, I'll be cleaning mine tomorrow as well I think. Also dies on the dualler in 5th when you put your foot to the floor to overtake. then picks up then dies then picks up then dies you get the picture.