2003 4runner Sport w 4.0 V6: I’m having problems with idiot lights coming on—the check engine and VSC trac lights. Mechanic says that’s he’s seen a knock sensor code previously. I’m getting symptoms of knock sensor trouble, including the lights. I replaced gas cap, but still having problem. The issue is this: the truck runs fine, for about 6-8 startups, then the lights go off, and I can feel shuddering and sometimes balky to start—knock sensor symptoms. Does it make sense that the knock sensor is functioning intermittently? Is it slowly going bad? Could it be the wiring harness for the knock sensor and not the sensor itself? Any help greatly appreciated. I’ve looked in the archive, but see nothing about this intermittent KS problem. By the way, my MPG is 18 city and 24 highway, if that helps.
Knock Sensor intermittent failure?
- Thread starter tifosi4
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BlackWorksInc
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Do you happen to remember what the DTC was specifically? It would help maybe narrow it down. If the vehicle is sputtering/shuddering it could be due to a misfire (which could be caused by a failing sensor, but it could also be a symptom of a larger issue.) Either way, it's going to be a bit of a pain to diagnose if it is intermittent. I have seen issues with the wiring harness before in a Tacoma and in other vehicles, I have also seen the sensors go bad (big issue for the GM V8's, easy to fix though.) Unfortunately on the 1GR-FE there is a coolant pipe that blocks the knock sensors, so its a pain to replace them.
We kind of need the DTC to narrow down which way to approach the diagnostics.
We kind of need the DTC to narrow down which way to approach the diagnostics.
Update on Knock sensor (?) trouble
I took my truck to my mechanic. He tried to read code. But, since I had disconnected battery to clear code, it was not stored. HOWEVER, his Snap-On scanner did generate a code on its own--the 1336 code. He said I need to come back to have it cleared, or maybe have work done--replacing yaw sensor. I made appt to return. Then got home and researched--it's the yaw sensor calibration code. I'm headed to Toyota dealer tomorrow to have it cleared (calibrated). Next question--should I trust this mechanic any more? When I called him back about it, he was nice enough, but seemed a little put out when I told him what research revealed. Should I go to Toyota dealer when what looks like the knock sensor is causing CEL again? Or can I go to independent mechanic? Thanks again for your advice and help.
I took my truck to my mechanic. He tried to read code. But, since I had disconnected battery to clear code, it was not stored. HOWEVER, his Snap-On scanner did generate a code on its own--the 1336 code. He said I need to come back to have it cleared, or maybe have work done--replacing yaw sensor. I made appt to return. Then got home and researched--it's the yaw sensor calibration code. I'm headed to Toyota dealer tomorrow to have it cleared (calibrated). Next question--should I trust this mechanic any more? When I called him back about it, he was nice enough, but seemed a little put out when I told him what research revealed. Should I go to Toyota dealer when what looks like the knock sensor is causing CEL again? Or can I go to independent mechanic? Thanks again for your advice and help.
BlackWorksInc
New member
Hmm, well that's a bit tricky...
P1336-Crankshaft Position (CKP) System Variation Not Learned
C1336- Zero Point Calibration of Acceleration Sensor Undone
The P1336 is not used by Toyota it seems (at least no mention of it is found in TIS when I search it), presumably because Toyota does not allow any variation in their readings; while other manufacturers require you to relearn them with a scantool somehow.
The C1336 is a common DTC set by Toyotas for the Zero Point Calibration being lost/corrupt and your vehicle is a 2003. The 2003 & 2004 Skid Control ECUs are notorious for being sensitive to Battery Voltage changes. If the battery drops to around 12.0v or lower, the ZPC is reset for some reason. I have even had the factory scantool reset the ZPC when I cleared codes on my own 2004, so it is possible the mechanic either ran the battery too low and/or when he cleared the codes he reset your ZPC. The good news is that it's an easy fix that they should have been able to do with the Snap-On tool, but is doable with a paper clip and/or the factory scantool.
As for trusting your mechanic... I couldn't tell you one way or the other?
Online research indicates that it's the ZPC. Not always reliable, I know. But I'm going to dealer tomorrow for calibration. Re: your suggestion to test resistance on Knock Sensor wire--can that be done without taking the thing apart? I'll have dealer do it if that can be reached without too much work. Thanks again.
