p0335, crankshaft position sensor help
 

Hi, this problem is occuring on a 2007 Elantra GLS; we're throwing code p0335 - the car has trouble starting, but it idles just fine, and operates fine under load up to 2500 rpm. After 2500, usually around 27-2800rpm it starts balking and throwing major hissy fits. No power, engine lopes, just really not fun to drive at all. :)

We've done a complete tune-up on every other area of the car to make sure as we go down the list trying to fix this, nothing simple has been overlooked (so once we clear the code everything else is up to par at the same time). There's 30k miles on it right now, and I'm hoping replacing the sensor will fix it, but I'm slightly worried that it may not be that simple. Has anybody else ran into this, and what experience did you have with it?

Oh, and I tried asking this on another Hyundai forum, and the general consensus was 'um, why not take it to a mechanic?'. I live just under 200 miles east of Vegas, in the desert. There is no Hyundai certified mechanic out here, and driving the car at 20mph into the city is out of the question. If we can, we need to fix it ourselves, so any and all help is greatly appreciated.

Replace the sensor...
 

The symptoms you describe are consistent with a failing crankshaft rotation sensor, but 30K is much earlier than for one of these to go bad than I've typically seen. It could be tooling around in the desert heat has hasten it's demise. At this mileage, this should be a warrenty repair at the dealership, but like you say, a 400 mile round trip may be more hassle than it's worth.

This is a relatively easy remove and replace procedure. If you are buying an aftermarket sensor (which I assume), make sure the gasket (or rubber o-ring) and the mounting bolt match the ones on the original sensor. This sensor is used in several application and the required bolt length can be different, but some aftermarket kits provide only one "standard" bolt which may work right or may not. Use the old bolt if they do not match. Also, sometimes the o-ring gasket will stay stuck in the mounting hole and will keep the new sensor from extending all the way into the hole. The engine may not start or will run like it has a bad sensor. Make sure the hole is clear of any obstructions before inserting the new sensor. Detailed instructions for making this repair are at http://www.hmaservice.com.

Good luck.

Much appreciated, Ken. We've already got one on order from Napa, SMP #PC528, same as the one coming out.

Quick question, I pulled it out earlier just to make a visual inspection that there was no physical damage to the harness, connector or unit itself and there was no o-ring on the sensor or in the mounting hole whatsoever. Could that be a factory oops?

This is a "Hall's effect" sensor, which detects the passage of a metallic object through a magnetic field. The sensor generates the magnetic field, the metallic objects are teeth on a target wheel mounted on the flywheel or flex plate assembly. Every time a tooth passes close to the sensor, the voltage state of the sensor goes from low to high and back to low, which is a wave form signal the PCU can use to track the rotation speed of the engine and the position of the crankshaft. Generating the field also generates heat (in an engine that is already a hot environment). It's been explained to me that over time, heat breaks down insulation inside the sensor and they fail. Some makes are worse than others. I've never replaced one on any Ford I've owned. I have a GMC Canyon at work with a 3.5-I5 engine that burns up one every 25 to 30K. If you read related threads on this forum, they seem to fail more often in Accents than other Hyundai models. Every one I have replaced looked pretty much the same as new sans oil and grime.

This could be a Ken99 oops. I thought there was a Hyundai TSB on this topic warning about errant o-rings on CKP sensors, but I cannot find it at the HMA Service site. I've worked on so many vehicles for family, friends and neigbors the past year, this could have been with another make. At 55, I don't remember as well either. I would simple make sure what you stick back in the hole matches what you took out.

Don't worry. ;) At pushing 30, I can hardly remember my age or birthday anymore, except for my wife who delights in reminding me (because she's younger). Let alone what day it is....

I'll post back if a ring comes with the new sensor tomorrow. After you mentioned that I ran through my head a few dozen times whether or not it might have just fallen out and I didn't notice it. The CPS is tucked in there fairly snug after all.

P0335
 

The blog post below might be of help
https://www.dreamlandmotorworks.com/...i-elantra.html