So this is weird...

[nthach]

I worked on a friend's 1998 Chevy Tahoe - his dad took it into Midas and a hack job local shop for new cats and cylinder heads a while back - truck was losing coolant and I saw lots of Dex-Sludge form. The hack job shop replaced the heads but didn't use the newer Fel-Pro PermaDryPlus LIM gaskets. I replaced those and I got the truck to fire up on the first try. Of course DTC P1345 - cam/crank correlation was set and I did replace the knock sensor with an aftermarket one. Last week, he said the truck was feeling sluggish and he could smell gas - misfire. I pulled codes, and I saw a P0326 DTC show up along with the P1345. I finally figured out how to get TorquePro to show the GM CMPRET PID to get the engine "re-timed" and we retimed the motor at Costco's parking lot - we needed to get wiper blades, go figure. The truck was finally running smoother.

And then on the drive home, I saw the CEL turn on, then turn off. A mile later it flashed and I knew something was wrong, ECM logged P0302 and P0304 - but the knock sensor P0326 DTC was gone! Turned out whoever replaced the heads or the plugs and wires routed the #2 & 4 wires against the exhaust manifold. I replaced the passenger side bank of wires and the CEL was off after 2 miles of driving - I assume the misfire monitors didn't pick up anything. He ordered AC Delco's professional line, the wires I pulled were Prestolite, they looked the same.

My question is - could a shorted/burned plug wire send stray voltage through the engine block and cause the ECM to think the knock sensor is going bad?

 

[Johnny2Bad]

Knock Sensors are notoriously unreliable. Think about it ... it's looking for an unusual vibration, possibly in a narrow audio frequency band, in a world of vibrations of a host of audio frequency bands. It's little wonder they are often fooled or simply don't work. With a KS fault, I would think almost anything is possible. I also would not worry about it or read too much into it. She works now ... problem solved, move on.

 

[nthach]

As long as the truck passes smog on both the sniffer and OBD readiness, I'm happy.

 

[circuitsmith]

A damaged ig wire that's making sparks in the engine compartment can radiate EMI that can be picked up in other nearby wires.
The knock sensor generates a small electrical signal that could easily be interfered with.