P0339 - Intermittent Crank Sensor Error - Not What You Would Think

[ostmike 35]

Last summer and into the fall OST began receiving phone calls from various shops around the US with technicians asking if we could assist them with resolving a p0339 CEL that was putting their customer cars in limp mode. We recommended replacing the crank sensor and all indicated that they had already done that. Several shops indicated that they had also replaced the wiring harness and eventually the PCM. I suggested trying an oscilloscope on the crank signal wire. I did not hear back from these shops and did not give it a second thought - until it happened to us!

Long story short we replaced the crank sensor, made our own crank sensor harness to the PCM, replaced the engine bay harness, replaced and reflashed the PCM. Nothing permanently resolved the issue.

The difficult part is once we made a change (like a new sensor) the problem went away. We actually dyno tuned the car before the incident popped up for the first time. This made it particularly difficult to diagnose. We even switched to tuning with HPTuners and that appeared to resolve the issue for almost a week but the issue returned. Using my Witech I could watch the crank signal and it was clean. On occasions I would see the crank signal deviate from a clean square wave and throw the p0339.

We examined the tone wheel the best we could through the crank sensor hole and all the teeth were intact.

I eventually called back the shops that had this issue previously and none of them had resolved the issue. I was looking for a common denominator. All of the cars had an aftermarket crankshaft. The aftermarket crankshaft in all the vehicles was from the same vendor. The crankshaft vendor purchased the tone wheels from the same supplier.

The resolution after too many hours of troubleshooting was to remove the engine, disassemble the bottom end, remove the crank and replace the aftermarket tone wheel.

Once the defective tone wheel was removed and examined closely (with a magnifying glass) what appeared to be a manufacturing defect became more visible in the gaps between the teeth.

A very costly fix.....

I just wanted to share in the event someone else is going through the same issue.

Update: I just wanted to add that this troubleshooting and eventual resolution would not have been possible without the perseverance of our shop manager and Lead Technician - Micah Doban. His willingness to work extra long hours and superior troubleshooting skills are a major asset to our shop and to the high performance auto community.

[Knownman 23]

Fing aftermarket!

Nice bit of troubleshooting there Mike.

[StevoHemi 113]

Way to go Mike!

Stevo

[toofart 148]

Shared knowledge FTW. Thanks Mike.

[El Diablo 72]

So what brand crankshaft's was the issue with ?

[Yellow Jacket 26]

Knowing Mike, he won't say. He's more interested in helping others by putting the knowledge out there than stirring up drama.

[ostmike 35]

So what brand crankshaft's was the issue with ?

Just to be clear it was not the crankshaft manufacturers fault. It was the tone wheel manufacturer.

What makes it difficult for a small business like us is that this cost OST several thousand in labor and parts to resolve. I can't really charge the customer. The engine builder and the crank manufacturer are not at fault either.

The tone wheel manufacturer did offer a replacement tone wheel at no charge

I'm just thankful we figured it out! It was a bugger.....

[El Diablo 72]

Just to be clear it was not the crankshaft manufacturers fault. It was the tone wheel manufacturer.

What makes it difficult for a small business like us is that this cost OST several thousand in labor and parts to resolve. I can't really charge the customer. The engine builder and the crank manufacturer are not at fault either.

The tone wheel manufacturer did offer a replacement tone wheel at no charge

I'm just thankful we figured it out! It was a bugger.....

I wasn't asking to cause any drama, just curious as to who made the reluctor wheels for future reference. Just in case I ever run into this issue.

[Mopar408 22]

Thanks for sharing Mike!

[Hemi31 194]

Were the tone rings manufactured about 3 years ago?

[ostmike 35]

Were the tone rings manufactured about 3 years ago?

No. According to the tone wheel manufacturer they were made less than a year ago.

[Hemi57 51]

Mike - AKA Sam Spade FTW

[ostmike 35]

Here's a pic of the tone wheel. Look at the gap between the teeth.

[no1special 36]

Holy crap!!!! Wow....I can't believe you figured that out. That's insane the lengths you went to get it done. That is absolutly golden info for anyone with this problem. Very very good info mike, thanks for sharing