My wife drives a 2005 Kia Picanto 1.1 with the Epsilon engine that has started to misfire and judder. Off the top of my head, I diagnosed a faulty ignition coil pack and used a Foxwell device to read the fault codes, which showed ‘P0336 – Crankshaft sensor A circuit out of reference’. I paid £48 for a new sensor and had loads of fun removing all the drivebelts, pulleys, etc, to access the sensor, which was under the lower crankshaft cover! I discovered the crankshaft pulley bolt was loose and had caused the ‘chopper’ plate to wobble slowly, rubbing off the top of the sensor until it could no longer function.
The Picanto had a new cambelt fitted shortly before we purchased it and the garage had fitted the bolt totally dry. It had fine rust all over the threads. On reassembly, I used thread lock on the threads and gave the car a service. It now runs as smooth as silk. My Suzuki Alto has the sensor mounted externally and uses an axial ‘chopper’, but seems to have come from a similar design shop. The Daewoo Matiz engine also has many similarities. Tony Nicholson
This is quite a common design across many engines and, as you have proved, the securing and tightening of key component bolts is crucial when carrying out work such as a timing belt replacement. This information will hopefully help other readers facing a similar problem.
Tony Nicholson’s photo of the sensor.