QuestionI have a 2001 Santa Fey 2.4 auto transmission. When the car has been sitting a while it drives fine. Once it has warmed up, I will loose all of my gears except 3rd. I can manually shift info 2nd, but can't get to 1st or 4th. If I shift it into 2nd gear, then move it back into drive, it will jump back to 3rd. This is a little scary on the expressway when it jumps from 4th into 3rd. But it does give a little warning that it's about to go, it will jerk a little so I do have a second to slow down before it goes into 3rd. If I turn it off and turn it back on it will be ok for a minute, but the only way to correct it is to let it sit for a while. I haven't had any diagnostic codes run on it. My check engine light has been on a while, before this started happening, and autozone ran the code then and told me i had insufficient flow to the EGR valve. This was quite a while before the transmission problems began. Are these problems related? any ideas? thanks!
AnswerI also received your follow-up with the codes P0401, P0442, and P0715.
You are correct that P0715 is for an abnormal reading from the input speed sensor and is the only one relating to the transmission. You got excellent chances that replacing the input speed sensor will cure the transmission issues.
The P0401 for the EGR system is much trickier. Although the standard definition for this code is insufficient EGR flow, Hyundai uses it to refer to any abnormality in EGR flow. To determine the issue, you'll need to diagnose the EGR system.
If you pinch the yellow striped hose on the throttle body, the EGR valve should open, causing the engine to idle poorly. If it does, you know that the hoses are intact, the intake passages are clear, and that the EGR valve itself is working. In that case, you'd need to check the EGR solenoid and the vacuum release valve. If pinching the yellow striped hose doesn't make the engine idle poorly, you'll need to investigate whether the hoses are all connected and in good condition, whether the EGR valve itself is stuck, or whether the intake passages are clogged.
P0442 refers to a small evaporative system leak. This could be caused by a loose or misinstalled fuel cap, or by an actual leak in the evaporative system. Before going through the time or expense of diagnosing this issue, you should probably clear the codes and see if this one returns. If not, it's fairly safe to presume it was causes by a fuel cap issue.
