P0336 Engine Code What’s Causing It

Posted in Internal Engine Parts

I have a P0336 engine code. My vehicle is a 2004 Chevy Venture van (3.4L V6 FWD). I had this code diagnosed and it pointed to a bad crankshaft positon sensor. The van has two of these sensors. I had both replaced with aftermarket parts (non oem). After this service was done, I am still having this same code coming back. The symptoms are these: rough idling, what seems like intermittent misfire, when I put the van in reverse gear, the misfire is far more noticeable. So much so that sometimes, the engine will stall in reverse gear. It has never stalled in drive gear but there still is a bit of misfire at idle or even at highway speeds. Both sensors have been changed and code cleared only to come back to same code after service. Any idea what’s causing this? Thanks in advance.
The sensors were installed at Canadian Tire. I did not tell them to diagnose the problem but just change the sensors as I knew ahead of time they were bad from reading the DTC.
Im not sure if the new sensor is or is not installed correctly. My symptoms on the van are still the same as before the installation. If the sensor is bad, why does it not give me misfires in Drive gear (well, not as much anyway) versus the reverse gear. The reverse is where the misfire becomes really noticeable.
Also, is there a way to test the theory that i have a bad crank sensor at the flywheel? I do have a windows based DTC scanner that can minotor live data. Can this be used in some way to know for sure that a wiring harness may be the culprit?
I have tried to wiggle the wire for the 24x sensor (i believe this is the A sensor, the one behind the balancer) but have not yet tried this with the 7x or the B sensor. I don’t think my scanner has an actual crank sensor monitor, can i just monitor the engine rpm to test the crank sensor? My code i got is showing the 24x sensor is the bad one. The wires for it seems to be ok. Wow, i wish i could discuss this in a thread or a forum.
I should also had that since the two sensors were changed, a CASE relearn has not been performed yet. I am not getting any code telling me a CASE relearn is required.

There are 2 Answers for "P0336 Engine Code What’s Causing It"

    1. Kyle says:

      Who installed the sensors ??

      The sensor installation is Critical… There is a precise air gap between the sensor and flywheel that Must be correct…

    2. mike d says:

      another problem with the 3.1 and 3.4 engines is the wireharness running to those sensors chaffes. Especially the one behind the harmonic balancer. this one if it physically had broken in the past may have knicked a wire going to the sensor causing no electrical signal back to the computer. Most likely though, the installer did not check to see if the sensor was lined up correctly before installing the balancer again and broke the new sensor.

      with the symptoms you are describing, it sounds like the sensor wires are messed up on the crank sensor which is not behind the balancer. This crank sensor which you have had changed, sounds like the wireharness going to it has chaffed wires. when the vehicle goes in reverse the engine torques in the opposite direction than when it is in drive. When the enginge torques in the direction which causes the missfires, the wires are moved in a way causing the chaffing to ground out the crank signal to short to ground creating an unreliable signal to the pcm causing the pcm to no know where top dead center is making it have to guess when to send the spark and fuel. this will be a missfire due to computer vs. engine timing. i would check for a short in the wires for that sensor. this is a very common problem for the 3.1 and 3.4 motors.

      Yes while graphing the crank sensor outputs wiggle the wire harness and see if the graph changes. watch the graphs while you place it in reverse as well as this is the position you are having the most problem in. Also do a visual inspection of the wireharness by the sensors and look for chaffing or missing insulation and or bare wires.

      I hate to say it but you really have to graph that one and see what it is doing. one thing also is that the one behind the balancer usually has 2 different sensors that can fit there. if the wrong one was placed on it then the computer won’t recognize it.. but it sounds like a wiring issue being that when it is placed in reverse it causes the problem more. i would ohm out the wires from the sensor to the pin on the computer.