Car Mechanics (UK)

Camshaft code


QI have owned a 2015 Hyundai i20 SE MPI 1.2 from new and covered 39,000 miles. About four months ago the yellow MIL engine light came on and was given a diagnostic­s check by the Hyundai main dealer.

Subsequent­ly a new exhaust camshaft position sensor was fitted, but the MIL engine light returned after five weeks. After a return to the garage, the fault was the P0017 camshaft position correlatio­n sensor again at fault. This was duly cleaned and after checks the car returned to me.

After three weeks the warning light had returned and because of Covid-19 the car was taken for a diagnosis check to a local independen­t garage. Their reply was to go back to the main Hyundai dealer as the diagnostic­s produced the same fault. Can you suggest any other possible reasons for this engine malfunctio­n. Paul Lingard

AThe full descriptio­n of the code P0017 is Crankshaft position/camshaft position, bank 1 sensor B – correlatio­n. This does not necessaril­y indicates a faulty sensor but more that the camshaft or crankshaft sensor correlatio­n is incorrect. This may be due to the cam chain having stretched or the tensioner being ineffectiv­e and this should also be considered.

A faulty camshaft sensor would throw a code such as P0342 or P0343 indicating a circuit performanc­e problem.

As the camshaft sensor has been replaced, then it must also be considered that either the crankshaft sensor, the wiring loom, or the ECU is the cause of the fault code. Either this or as mentioned the timing chain or tensioner is at fault. Given the low mileage of the vehicle I would be surprised if the problem was related to the timing chain, but this cannot be ruled out.

You have mentioned that the camshaft sensor was cleaned, and I presume this referred to the electrical connection as any external cleaning of the sensor would have little effect, unless of course it was incorrectl­y fitted and was not fully detecting the camshaft.

Given that this did appear to prevent the fault from reoccurrin­g for a few weeks, I would make a thorough check of the loom and the cam sensor connecting plug, and also check that the sensor does appear to be sitting fully into place to ensure that this is not the area of the problem.

If no faults can be found I would consider renewing the crankshaft sensor and if the problem is not resolved then I would remove the camshaft cover to check for any slack in the timing chain. Unfortunat­ely this is not easily accessible without stripping off the front of the engine and so a quick check of the timing is not possible but may be required to fully determine the source of the returning code.

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