Any mechanic to help troubleshoot electrical issue?
 

Anyone on here know how to troubleshoot electrical issues on a mazda? Got a P0328 (knock sensor 1 circuit high input) after replacing my spark plugs, but CEL still there after i switched them back to the original ones. OR any shop recommendation? Went to one near my house and they couldn't figure it out...

What year, make and model of Mazda?

How is the car reacting (other than giving you a code)?

Have you tried disconnecting the negative side of the battery, then stepping on the break, then reconnecting the battery, to see if the code will go (and stay) away?




humfrz

2011 mazda 2... CEL will not go away... tried disconnecting the battery and clearing it via OBD2 reader... cars sounds and idles fine, but drives in limp mode aka less power

hmmm - have you tried asking over on the Mazda forum?

It may be time for a trip to the shop - :iono:


humfrz

i went to a shop near my place, and they couldn't figure it out.... mazda forums are very dead, and not very technical

OK. You might test/replace (or have done) the knock sensor itself.

https://youtu.be/j-Wr2VMvfbc


humfrz

If the engine is obviously not knocking and all the wires and connections look good then like Hum said it is time to try a new sensor.

First off, it's not the plugs.

I suspect that while working on the engine, you may have accidentally damaged the knock sensor connector or wiring. "sensor high" is either an open, or short depending on the design of the system itself. Usually it means "open" (disconnected, burned out, wire cut...)

Find the sensor itself and then consider how the wiring may have been damaged.


If I was the shop, at a minimum, I'd plug in a known good sensor and fire up the engine. If it doesn't throw a code then the sensor went south. If it does, then it's the wiring. Buy a new sensor and be prepared to eat the cost. It's still cheaper than an oscilloscope. ;)

correct, i just swapped the old plugs back in for troubleshooting purposes... the knock sensor is not known to go bad at 60K miles...and it just go happens that it happened after i did the spark plug change... the knock sensor is connected to the PCM which sits on top of manifold... i had to push that aside when doing the spark plugs, but there was enough slack in the wire... if it is the actual wiring to the PCM, i wouldn't even know how to troubleshoot it...

look there. Busted wire... loose connector... You're going to need a multimeter to do some continuity checks. If this is Greek to you then don't even start. Take it to a better shop and start by giving them the whole back story.

it's pretty much greek to me haha... even the first shop i brought the car to didn't know how to do electrical work....

wires can look just fine, but somewhere in the loom is a break. have you tried a continnuity check from the sensor to the ECU?

i am a total noob when it comes to electrical lol

found a shop... charged me $180 to troubleshoot and fix the issue

well, what was the problem?

the knock sensor wire going to the PCM was damaged... my guess was right lol... the guy said it looked ok physically, but found out it was damaged after running some tests

Your guess?