Vehicle details: Skoda Octavia
Symptom: Engine stalling
Author: George Cameron | Ibrox Vehicle Repairs & Diagnostics Ltd.

Skoda Octavia | Crankshaft reluctor

The fault

This vehicle was recovered from another garage after having its engine rebuilt. It would start and then cut out.


There was a fault code of “engine speed sensor implausible signal”. We checked the output of the crankshaft position (CKP) sensor and found an irregularity in the waveform:

crankshaft revolutions waveform

Figure 1: Several crankshaft revolutions. Upper trace: Camshaft (CPS) sensor. Lower trace: Crankshaft (CKP) sensor.

We zoomed in to get more detail:

crankshaft revolution waveform

Figure 2: Zoomed in to a single crankshaft revolution.

The crankshaft waveform (lower trace, blue) shows an obvious fault 7 to 8 teeth after TDC. Removing the crankshaft sensor and looking with a borescope, I could see that the reluctor ring had two slightly bent teeth.


I removed the sump and realigned the two bent teeth, and all was well.

Total time for diagnosis and repair: 1.5 hours

Download the PicoScope data files of the waveforms featured in this article:

psdata skoda-crankshaft-reluctor.psdata 15 KB


2 comments | Add comment

Trevor Grigg
July 03 2010

Good posting George.
A fairly straightforward fault,but a credit to you for a well structured approach to the problem.
The more I read these postings dipicts how good Pico and the techs are, convincing me more so to sell the old fluke 196 and move up to Pico.
Regards Trevor.

Mick Hursey
July 03 2010

Hi, Had exactly the same problem on an XC90 only without a scope it three days to find! At least it got me my new Picoscope!!!

Your email address will not be published. Required fields are marked *

Case study: Crankshaft reluctor