My 2006 Chevrolet HHR is showing fault codes P301 and P1174. Code P301 indicates a misfire detected in cylinder 1, while P1174 points to an oxygen sensor issue. I'm trying to determine whether I should replace the spark plug or the fuel injector for cylinder 1. Can anyone provide guidance on which component is more likely at fault? Thanks for your help.
Is 'swapping for you' referring to replacing with a different brand or model of component? Clarifying this would help avoid confusion.
Simply replace one existing coil pack with another to test functionality.
I replaced the first cylinder's coil pack with a second one and left the rest unchanged. The fault code pointed to Bank 1, so I performed a visual inspection of all coil packs and used vacuum to clean them—no cracks or damage were found. I disconnected the battery before swapping to prevent electrical issues. Now I'm waiting for the system to reset and see if the codes clear. What should I do next? Should I replace all coil packs? Or consider cleaning or replacing fuel injectors? Any advice would be appreciated!
Did the misfire move to cylinder #2 after the swap?
No, the check engine light is currently off. I disconnected the negative battery terminal before swapping the coil packs, which reset the system. Now I need to wait for all parameters to stabilize and return to normal.
Hello! Today the check engine light came back on, and the code shows 'P301 – cylinder 1 misfire detected'. I replaced the spark plug last year, and I've only driven less than 20,000 km. Could this be a faulty spark plug? Or is it more likely a problem with the fuel injector or coil pack? Any suggestions would be greatly appreciated!
Swapping out the coil pack is usually the simplest first step. Try that before moving to more expensive repairs.