# Code reader says P0307 **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** yukon, gmc\ **Created:** [October 24, 2009, 4:57pm UTC](https://community.cartalk.com/t/code-reader-says-p0307/38562 "2009-10-24T16:57:21Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![phicks805](https://avatars.discourse-cdn.com/v4/letter/p/858c86/32.png) [@phicks805](https://community.cartalk.com/u/phicks805)\ **Post date:** [October 24, 2009, 4:57pm UTC](https://community.cartalk.com/t/code-reader-says-p0307/38562/1 "2009-10-24T16:57:21Z")
The service engine light is on, got a code reader and it came up with this code. We replaced plugs, distributor cap, and light still on, car runs really rough, what should we try next? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [October 24, 2009, 5:03pm UTC](https://community.cartalk.com/t/code-reader-says-p0307/38562/2 "2009-10-24T17:03:14Z")
P0307 indictes a misfire at cylinder #7. Did you try replacing the spark plug wire for cylinder #7? Tester ---
**Author:** ![phicks805](https://avatars.discourse-cdn.com/v4/letter/p/858c86/32.png) [@phicks805](https://community.cartalk.com/u/phicks805)\ **Post date:** [October 24, 2009, 5:05pm UTC](https://community.cartalk.com/t/code-reader-says-p0307/38562/3 "2009-10-24T17:05:39Z")
Yes we replaced the plug and wire for #7 ---
**Author:** ![cigroller](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cigroller](https://community.cartalk.com/u/cigroller)\ **Post date:** [October 24, 2009, 5:11pm UTC](https://community.cartalk.com/t/code-reader-says-p0307/38562/4 "2009-10-24T17:11:30Z")
Check the wiring/harness for the #7 fuel injector. Check the resistance on that injector. Swap the #7 with another and see if the misfire moves. A compression test on #7 cylinder might also be a good idea. ---
**Author:** ![phicks805](https://avatars.discourse-cdn.com/v4/letter/p/858c86/32.png) [@phicks805](https://community.cartalk.com/u/phicks805)\ **Post date:** [October 24, 2009, 5:13pm UTC](https://community.cartalk.com/t/code-reader-says-p0307/38562/5 "2009-10-24T17:13:30Z")
Thank you, we will try it ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [October 24, 2009, 5:14pm UTC](https://community.cartalk.com/t/code-reader-says-p0307/38562/6 "2009-10-24T17:14:59Z")
Check to see if the fuel injector for cylinder #7 is working. With engine running, take a long screwdriver or a length of dowel and put one end on the fuel injector and place your ear on the other end to act as a stethoscope. Can you hear the injector clicking rapidly? Now do the same thing to another injector. Does the injector for cylinder #7 sound the same as the other injector? Tester ---
**Author:** ![phicks805](https://avatars.discourse-cdn.com/v4/letter/p/858c86/32.png) [@phicks805](https://community.cartalk.com/u/phicks805)\ **Post date:** [October 24, 2009, 8:48pm UTC](https://community.cartalk.com/t/code-reader-says-p0307/38562/7 "2009-10-24T20:48:10Z")
Are you sure it has fuel injectors?? How do we tell? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [October 24, 2009, 9:33pm UTC](https://community.cartalk.com/t/code-reader-says-p0307/38562/8 "2009-10-24T21:33:17Z")
Yes. It’s fuel injected. The code P0307 is an OBDII code. All OBDII vehicles are fuel injected. Tester ---
**Author:** ![phicks805](https://avatars.discourse-cdn.com/v4/letter/p/858c86/32.png) [@phicks805](https://community.cartalk.com/u/phicks805)\ **Post date:** [October 24, 2009, 9:36pm UTC](https://community.cartalk.com/t/code-reader-says-p0307/38562/9 "2009-10-24T21:36:33Z")
Ok, but does it have 8 fuel injectors? My husband is used to working on our 88 pontiac GTA and the fuel injectors are all on top