P0867: How to Diagnose & Fix — Transmission Fluid Pressure

On certain 2020 Elantras the IVT (Hyundai's CVT) can store transmission codes and light the check engine lamp; Hyundai's campaign updates the transmission software and replaces the IVT when the listed codes show it may be damaged. On 2020-2023 IVT Elantras covered by bulletin 23-AT-010H, a faulty IVT oil pressure sensor can also set pressure codes, and Hyundai says to replace the whole IVT if slipping, shift shock, poor acceleration or failure to shift into gear come with them. This covers certain 2020 Elantra (AD) sedans with the 2.0L MPI and IVT (service campaigns T5B and 963), plus 2020 Elantra (AD) and 2021-2023 Elantra (CN7) with the IVT for the oil pressure sensor bulletin 23-AT-010H (dated August 2023; it lists the 2021 model year onward). Only IVT-equipped cars are affected.

On the 2019 Ascent the mid-joint of the transmission hydraulic pressure sensor harness was built with dissimilar metals - tinplate against copper. Galvanic action forms an oxide film at that joint, and the film corrupts the pressure signal the sensor sends to the TCU. When the sensor reports a pressure HIGHER than actual, the TCU commands the valve to reduce line pressure, and the Lineartronic's drive chain loses clamping tension. Slipping chain produces noise, vibration and hesitation, and continued driving in that state leads to loss of power. Recall population was 76,842 vehicles. This is a separate campaign and a separate root cause from the later TR690 chain-guide/TCU-programming recall (21V955 / WRK-21) - that one is a programming issue at clutch engagement, this one is a corroded sensor harness.

Hyundai TSB 23-AT-010H (August 2023) covers 2020MY-and-later Venue (QX) equipped with the IVT, alongside Elantra, Accent and Kona IVT models. The IVT driven-pulley oil pressure sensor (part 48885-02300) can fail electrically or read out of range, turning on the check-engine light with P0845 (sensor output at or below 0.27 V or at or above 4.50 V), P0846 (sensor output 2.5-3.5 V with target-vs-actual driven-pulley pressure off by 4 bar or more) or P0867 (target vs actual secondary pulley pressure differing by more than 7 bar). The bulletin exists because dealers had been replacing whole transmissions for what is a sensor fault: when the vehicle has ONLY the DTC and no drivability complaint (no slipping, shift shock, poor acceleration or failure to engage), the sensor is replaced through the IVT oil pan with a new pan gasket and 7 quarts of fluid, then 'Oil Pressure Characteristics Input' and adaptive-value relearn are performed with GDS-M. If drivability symptoms are present the whole IVT is still replaced. Note P0867 also appears in the T8X campaign list for 2020-22 units, so an owner with P0867 should have both bulletins checked.

On the E-Ray only, the 8-speed dual-clutch transmission carries an auxiliary fluid pump so the gearbox stays pressurized while the car is moving on electric power alone in Stealth or Shuttle mode. GM published Bulletin #25-NA-278 for 2024-2026 Corvette E-Ray models that display a Service Transmission message in the Driver Information Center along with an illuminated Check Engine MIL, with DTC P1955 (Transmission Fluid Pressure Relief Valve Performance) and/or P0867 (Transmission Fluid Pressure Performance) stored in the TCM. GM identifies the cause as auxiliary pump cavitation traced to the transmission pan fluid filter. This condition is specific to the hybrid E-Ray driveline and does not apply to the Stingray, Z06 or ZR1, which have no electric-only drive mode and no auxiliary pump duty cycle of this kind.