arclightzero

My HHR started throwing the knock sensor low voltage code. I bought a new sensor from NAPA, but now I cannot find the sensor on the motor. Has anybody ever changed one of these out? I assume it is an easy process, but I don't know where to look for the thing.

Thanks!

ChevyMgr

By the oil filter.

arclightzero

Thought I'd give a quick update now that I replaced the thing on Saturday.

Bought a NAPA sensor for $33. I saw them cheaper elsewhere, but with shipping costs NAPA was still a better deal, plus I got it the next day. Useful to have the part in hand before you start, especially since it helps to know what you're looking for.

The sensor is located directly above the starter, bolted to the block and is only accessible from under the car. No matter what angle you try, you cannot see the thing. The best way to find it is to find the wiring harness for it (which is distinct looking compared to some of the others) and follow it with your fingers up to the block. If you shine a shop light along the starter it's easy to find the harness.

Once you find it, and making sure your battery is disconnected since you're working around the starter terminals, use a 13mm gear wrench to loosen the thing. I found I could turn the gear wrench about a 1/4 turn under there, so once you loosen it it's easiest to just use your fingers to back the bolt out all the way. Pluck the harness from the bracket (it's held in place with a plastic retainer that pulls free from the bracket) and disconnect it from the plug.

The fun part is trying to blindly find the hole when you snake the new one in there. There was a near by bolt hole that was the wrong size, but after a little trial and error I managed to get it into the original hole. Again, finger tightened the thing and snugged it down with the gear wrench. Plug the new sensor in and press it back into the bracket. Reconnect the battery and lower the car back down. You should be done.

Now if you have the ability to reset the CEL, do so now. Otherwise after three starts without a re-occurrence of the code, the CEL will go out on its own.

And that's that! Not too painful, and it only takes $33 and about a half hour of work

J W Davis

Great post, thanks for the info. It will help an untold number of people who can come here and find answers. Is'nt this what it is all about?

Santa Fe Jay

Hey guys, Thank You a bunch for the information. My 06 turned on it's annoyance light and it coded for the knock sensor. AutoZone had a Duralast for $32 and now I have this shiny new 13mm gear wrench as a bonus. You can see it from above, but you might as well plan on raising the car, putting on your safety glasses to keep dirt out of your eyes and doing it from below. Unlatching the electrical connector was more difficult than changing the sensor part. If you don't have one yet, those LED lights that you wear on your forehead are a great help.
Always disconnect the battery first!

arclightzero

Funny, you are right about the connector being more difficult to remove than the sensor itself. I couldn't easily get two hands up there to get a good angle on it and beat up my knuckles something fierce trying to get enough leverage to depress the lock and pull it back from the harness.