Q: 2004 jag xj8 4.2 v8 auto trans 5spd had trans fluid leak. lost approx 6qts. repaired leak and filled per instructions on alldata w

The two codes, P0736 and P0730 overlap to some extent insofar as possible faults. If the transmission fluid got really low, the transmission might have overheated with several consequences: burnt fluid; mechanical damage, case/part distortion, damage to hydraulic seals on clutch pistons, and so forth. Although you added a lot of "new" fluid, check the fluid condition. You might have to remove the pan and check for debris and check for a clogged filter. Debris and a clogged filter will cause non operation. If there is debris and/or the fluid is burnt or contaminated, you’ll have to change the fluid yet again to rule that out as a cause. Of course, if you find a lot of metal debris, you might be better off just rebuilding the unit and not attempting to further diagnosis a unit that already evidences obvious damage. Check the fluid level. Check for burnt wiring, particularly to the shift solenoids, and faulty circuitry. Test the shift solenoids (check resistance of coils). If none of the foregoing generates a result check hydraulic gauge pressures against factory spec in P, D, and so forth. If gauge pressures are off (out of range), that means the oil pump might have gotten damaged (perhaps run dry?), the valve body is defective, hydraulic passages are blocked (that debris issue) and/or the heat caused damage to rubber piston seals causing pressure to bleed off. With inadequate pressure, clutches won’t apply and the car won’t go into gear.

If you desire, all of the foregoing diagnostic steps can be performed by a mobile certified mechanic. Please simply request a shift diagnostic. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.