Knock sensor CEL

[Jord]

Heading to work the other morning, the CEL came on as I first turned on the car and remained on for approx 1 minute before going out again and staying out for the remainder of the trip, forgot about it until it popped up again yesterday.

Coinciding with the CEL the engine felt very sluggish and a bit jerky, so I figured it would probably be a knock sensor issue retarding the timing and cutting boost. Checked the ecu for codes this morning and sure enough code 22 - knock sensor.

Does the ecu flag a CEL when det is picked or is it normally just when the the sensor is starting to fail?

Can replace the sensor easily enough myself if that\'s the problem...

Car in question 1999 Legacy B4 TT run on BP98 95% of the time.

[serunox]

 Jord said:

Does the ecu flag a CEL when det is picked or is it normally just when the the sensor is starting to fail?

Cant truly answer that one as I don\'t know too much about the ecu\'s.However same problem happened with me, checked the codes and was 22 as well.

Went one like that for probably a week when the CEL came on and off intermittently, mostly when driving 100km/h.

Changed the knock sensor straight away which fixed the problem. CEL never came on again and no more sluggish or jerkiness.

So I\'d say replace it if it continues happening.

Just my 2cents

[Marky]

My understanding is factory ECU\'s won\'t throw a CEL for knock - it\'s only some reflashes that do

Time to get hands dirty

[Kiwi_Fozze]

Correct. Only the carberry project speed density tune and i think the group n tune built by subaru have it, carberry tune it can be turned on and off. Still fiddling with the fhi tune.

[Eight_dollar]

code 22 is logged when sensor resistance is out of spec - usually from a cracked sensor

22 will not log on OEM ECU with engine knock - ecu will just try to control the knock

replcement is only fix

skilled hands can swap these out in 15min - but i\'d allow yourself 2hrs (a cold engine is much easir to do this job btw)

only I/C need to be removed to access- its very small acess area

[Jord]

Thanks for the replies.

Ill pop into Subaru and pick one up on Monday, changing the sensor wont be hard, its getting the stoooopid TT intercooler back on that\'s the fun bit

[Marky]

Get silicon - makes it a literal 2 min job to remove or refit

[Eight_dollar]

lol - once you see where the silly sensor is you might drop the F bomb a few times

Getting old one out isnt too bad - but fitting the new one can be tricky

place the mounting bolt into the new sensor and lower it into place - 3/8dr "wobbly" extentions are great to get onto it

oh and make sure you torque the sensor up - 25Nm