8HP90 Tcc Solenoid, new and ready to install. Fits the 8HP90. Ships fast from the USA.
If your 8HP90 or Audi 8HP55A has started to vibrate at a steady cruise, holds RPM higher than it used to on the highway, or has logged a torque converter clutch fault, the converter lockup regulator is a prime suspect. This listing is the complete new ZF-branded solenoid set under ZF reference 1087298389, as pictured, not a single loose solenoid. The converter clutch regulator is in the set along with the line pressure and shift element regulators. The listing describes it as a replacement part made in China rather than a dealer-boxed original, so we say that plainly up front.
The 8HP90 is the heavy-duty member of ZF's first eight-speed family, rated for 900 Nm, and it locks its converter early and often to keep that torque from turning into heat. Lockup is not an on-off event here. A variable-force regulator in position B of the valve body sets the apply pressure on the converter clutch so the module can hold a small, controlled slip. On Audi 8HP55 valve bodies Sonnax identifies this regulator as EPC-TCC, N371; on BMW units the same position is EDS-2. Because the 8HP90 asks that clutch to hold more torque than any other first-generation unit, a regulator that loses its pressure range shows up quickly as slip, chatter or a lockup fault.
Rule out the easy causes first. Check the fluid level at the correct temperature and replace tired fluid, because degraded ATF alone can make the lockup clutch chatter. Inspect the mechatronic connector sleeve for leaks, a well-known ZF eight-speed pressure loss. With a capable scan tool, compare commanded and actual converter slip on a steady cruise. Once the mechatronic is out, test the B position regulator with the circuit board removed; the Sonnax ZF8-ZIP booklet lists about 5.0 ohms at 20 C and warns to use a meter that tests under 0.6 volts. If the regulator tests good, worn TCC circuit bores in the valve body are the next suspect, and a ZF8HP shift kit addresses those on first-generation units. Our ZF8HP solenoid symptoms guide and BMW shift problems guide lay out the checks in order.
The set is listed for the 8HP90 and the Audi 8HP55A, both first-generation ZF eight-speeds. It is not for second-generation units such as the 8HP95, which use different solenoid caps and a swapped B and D layout according to Transmission Digest. Some high-output models changed generations partway through production, so check before ordering. Match the cap colors and connector shapes in the photo to the regulators on your valve body, or send us your year and VIN and we will confirm. The rest of our eight-speed range is on the ZF 8HP collection page.
Drain the fluid, remove the pan and lower the mechatronic unit after unplugging the connector sleeve. Swap regulators one position at a time; the bores are not interchangeable and a misplaced TCC regulator will cause immediate lockup problems. Inspect each bore, lubricate fresh O-rings with clean fluid and tighten the retaining plates evenly. Replace the connector sleeve and the pan with its built-in filter while everything is apart. Refill with ZF LifeguardFluid 8, such as our 7-liter Lifeguard 8 fill, and set the level hot. Clear codes, reset adaptations and drive repeated steady-speed lockup cycles so the module relearns slip control. If you would rather renew the whole hydraulic control side at once, compare this with our 8HP90 solenoid kit.
| Fits | 8HP90 |
| Part type | Tcc Solenoid |
| Condition | New |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It is the full ZF-branded 1087298389 solenoid set shown in the photo. The converter clutch regulator is included with the line pressure and shift element regulators.
The listing describes it as a new ZF-branded replacement set made in China under reference 1087298389, not a dealer-boxed original. We state that so you can decide with the full picture.
The position B regulator. Sonnax identifies it as EPC-TCC N371 on Audi 8HP55 valve bodies and EDS-2 on BMW units.
No. Second-generation units use different solenoid caps and swap the B and D positions, so they need Gen 2 parts.
The connector sleeve, the pan with its integral filter, and the fluid. Use ZF LifeguardFluid 8 and reset adaptations after the repair.
