Hi All,

 

I found some similar threads about check engine light and knock sensors, but they seemed to be concerned with faulty sensors rather than an actual knock problem.

 

My situation is that I had the engine replaced recently on a 2001 Outback A/T (engine is rebuilt with 7/70 warranty). Shortly after it was replaced, the CEL started coming on intermittently. It seems random when it comes on and it can stay on for a whole triip (us 1/2 hr in town), or just several minutes. We also think that it is not running as smoothly as it should, though it is not terribel.

 

We took it back to the shop (not a Subaru one since there are none in the area) and they read the code and found it was engine knock. They reset it and said to come back if it came on again. It did, with the same code, but the light went off. They seem to be at a loss as to what to do.

What should I have them check? They do not have an exhaust gas analyzer, but I was under the impression that that was required for setting up engines these days.

 

Any suggestions most welcome...:-\

Was it the knock sensor that tripped the light?

What makes you think you have "an actual knock problem"? It's probably the sensor.

 

Replace the knock sensor.

 

If it was already replaced then make sure it's installed properly. Remove it, check the connector, clean the threads, mating surface on the block, and clean the sensor. Also, there's a very specific installation procedure. It is supposed to be installed only one way and at a specific torque.

 

All of this is covered in other threads on USMB, print those threads out (they have pic's too) and give to your mechanic.

While working as a tech in Subaru dealerships, I installed a large number of factory short block engines. EJ22 and EJ25 short blocks came with new knock sensors already installed. The point is, knock sensors and O2 sensors, IMHO are maintenance items and should be replaced at regular mileage intervals of 80 to 100 thousand miles. And definitely any time an engine is replaced.

Replace the knock sensor.

 

 

nipper

Thanks everyone for the replies. I thought that the mechanic meant that the sensor was indicating that the engine was knocking. Looking into it further, it seems that there is only one knock sensor code, so everyone's advice to replace the sensor seems reasonable. The CEL has been off for a while but it is maybe still prudent to replace it anyway.

 

Does anyone have any opinion about whether a $50 sensor would be any worse in terms of performance or reliability than a $90 one?

Thanks everyone for the replies. I thought that the mechanic meant that the sensor was indicating that the engine was knocking. Looking into it further, it seems that there is only one knock sensor code, so everyone's advice to replace the sensor seems reasonable. The CEL has been off for a while but it is maybe still prudent to replace it anyway.

 

Does anyone have any opinion about whether a $50 sensor would be any worse in terms of performance or reliability than a $90 one?

 

 

They are basically really simple devices. they are just a little peice of quartz that makes an AC signal that the ECU processes. I have yet to hear of this having to be an OE part. Check www.1stsuabru.com website just to see what sooby gets for one.

 

Otherwise I dont think it matters.

 

nipper

Probably should stick with an OEM sensor.

www.rockauto.com claim that the OEM part is: "OE Part # 22060AA070A {Knock Sensor #22060AA070}", and their price for that is only $42.89!