Check engine light came on and I had pep boys test it. These codes came back PO0303
and PO0171 how do I fix it?
P0303 is a misfire on cylinder 3 - check the ignition and injector on that cylinder.
P0171 means engine is running lean (probably related to the above).
Start by checking the tune of the engine, verifying with a timing light that all cylinders have spark. Since these are coil over plug, swapping cylinder 2 with cylinder 3 should result in P0302 in addition to P0303 DTCs being set. If there's a problem with the VVT (Variable Valve Timing system) then there should be a DTC associated with that as well.
If you have spark, then it goes on towards a faulty injector. If both spark and fuel are present, it's possible that the VVT (Variable Valve Timing) system is freewheeling cylinder 3. Usually that implies the hydraulic lifter seals are faulty though there should be a noticeable valve tap at idle.
In any case, testing out ignition then fuel then ruling out VVT-related issues should resolve the problem completely. I have seen many of these have problems with the plumbing to the valve lifters getting clogged and that results in a dead cylinder.
Oct 06, 2013 |
2005 Volvo S40