knock sensor/harness questions

[fan of fanboys]

so I just read through half dozen threads on topic on here but I have a few more questions

I don't know what code is currently being thrown, I'll head to part store after work and have them check

I have had check engine light for awhile and when it first started a few months ago was the p0171 lean bank 1. not sure MAF or throttle body had ever been cleaned so did that. did not resolve check engine but fuel economy went from low to mid 16 mpg to high 17mpg to low 18mpg, which is what I am currently getting.

I had the truck at the mechanic for something else about a month ago and he is the one who said I needed new knock sensors and harness. quoted me $1,500

truck is running fine, decent mpg, feels underpowered but then again I bought it with 248K miles and it has never felt powerful. I also had it for nearly a year before CEL came on

some posts on here have said the sensor themselves rarely fail and to start with changing just the harness

some say go ahead and go sensor and harness (oem, of course)

in my situation should I start with just the harness and then do sensors if needed? if it is driving well and decent mpg what seems most probable for failure?

I am in Cola, SC and 3 weeks ago I drove to Atl, GA and back and this past weekend I drove to Myrtle Beach and back. MPG and drive was fine (outside an unrelated issue, which I'll ask about in another thread as it is battery/alternator related)

anything I am missing just ask and I'll do my best to answer

 

[spartacus]

I believe this cel is for system to lean but find out if you have other codes.
I would check the pcv valve hose for oil, it could also be a vacuum leak or cat blockage or gas system leak or o2 sensor.I believe the knock sensor code is p0325.
1500 with parts and labor? you should read the forum and trouble shoot throughly or if you can't then get a second opinion from a different mechanic before shelling out the money.

 

[gamefreakgc]

P0171 is almost always a vacuum leak. Check for old cracked hoses or a failed gasket:

<iframe width="560" height="315" src="https://www.youtube.com/embed/9CPqbaSgcok?rel=0" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>

Also, buy a bluetooth reader and download the free Torque app. For $22 you can pull codes yourself as well as read other information about your engine without having to rely on what the part store guy thinks the problem is.

https://www.amazon.com/BAFX-Product...pID=416SaTHOpkL&preST=_SX300_QL70_&dpSrc=srch

If you do need a new knock sensor and harness which due tend to give problems with age and you don't end up doing it yourself, make sure they use Toyota parts. Aftermarket sensors don't always work right. If it's throwing the knock sensor code, 99.9% of the time it's the sensor and/or harness.

 

[fan of fanboys]

P0171 is almost always a vacuum leak. Check for old cracked hoses or a failed gasket:

<iframe width="560" height="315" src="https://www.youtube.com/embed/9CPqbaSgcok?rel=0" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>

Also, buy a bluetooth reader and download the free Torque app. For $22 you can pull codes yourself as well as read other information about your engine without having to rely on what the part store guy thinks the problem is.

https://www.amazon.com/BAFX-Product...pID=416SaTHOpkL&preST=_SX300_QL70_&dpSrc=srch

If you do need a new knock sensor and harness which due tend to give problems with age and you don't end up doing it yourself, make sure they use Toyota parts. Aftermarket sensors don't always work right. If it's throwing the knock sensor code, 99.9% of the time it's the sensor and/or harness.

going to buy that today, except I need the iOS version which is $27.

the OBD tool at advanced would not pull up a 1999 the guy said so I dunno what the code is

but I'll order this and then report back once it arrives

https://www.amazon.com/BAFX-Product...rd_wg=DqdJe&psc=1&refRID=ACHH1XX00SKQK9ANYE5M

^ that is a good one for iPhone?

a vacuum leak should hopefully not be too big of a deal to resolve

 

[Riceye]

Also, buy a bluetooth reader and download the free Torque app. For $22 you can pull codes yourself as well as read other information about your engine without having to rely on what the part store guy thinks the problem is.

That is a great app, which I use frequently for real time info. Bluetooth dongle is a practical device unless you stream content to your head unit via bluetooth. Wifi dongles are available, as well, and seem to work just fine.

Wifi obd2 reader

 

[gamefreakgc]

going to buy that today, except I need the iOS version which is $27.

the OBD tool at advanced would not pull up a 1999 the guy said so I dunno what the code is

but I'll order this and then report back once it arrives

https://www.amazon.com/BAFX-Product...rd_wg=DqdJe&psc=1&refRID=ACHH1XX00SKQK9ANYE5M

^ that is a good one for iPhone?

a vacuum leak should hopefully not be too big of a deal to resolve

I don't have an iPhone so I can't verify, but their bluetooth one works great. The reviews mention another app, OBD Fusion that might be worth looking at. Not sure Torque can use a Wifi code reader.

 

[Riceye]

Not sure Torque can use a Wifi code reader.

The app doesn't care. I've been using one for several years. Again, I have nothing against bluetooth, except that I stream from my iphone to my head unit via bluetooth. Can't do both.

 

[fan of fanboys]

it will arrive Friday, will post code once I know it


trying to head to gulches for memorial day weekend so like to have it cleared before then ha

 

[fan of fanboys]

So scanner arrived. It is p0330 code

So as long as not knocking (that I can hear) and mpgs aren't suffering am ok to continue to drive it? Any risk of damage?

And should I start with replacing harnesses and only replace sensor if issue persist?


Sent from my iPhone using Tapatalk

 

[fan of fanboys]

Specifically it says knock sensor 2 circuit


Sent from my iPhone using Tapatalk

 

[gamefreakgc]

So scanner arrived. It is p0330 code

So as long as not knocking (that I can hear) and mpgs aren't suffering am ok to continue to drive it? Any risk of damage?

And should I start with replacing harnesses and only replace sensor if issue persist?


Sent from my iPhone using Tapatalk

Depends really if you are ok with the possibility of having to tear down the engine a second time. Most do it all at once knowing that it'll be fixed.