Mechatronic · 01J

01J mechatronic replacement unit

The 01J Multitronic is a continuously variable transmission (CVT), factory code 01J. Its control unit and hydraulic control are combined in the mechatronic unit.

This page covers the typical symptoms, control faults, fault codes and the replacement units available for the 01J Multitronic.

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Technical overview

What the 01J mechatronic does

Instead of fixed gears, the Multitronic uses a variator with a link chain that changes the ratio continuously. Forward and reverse drive are engaged by multi-plate clutches.

Typical faults involve the transmission control unit, the speed sensors and the hydraulic pressure that controls the variator and the clutches.

Replacement units are identified by the OEM part number. Always compare the number on your unit before ordering.

Transmission family	01J (Multitronic CVT)
Also known as	01J
Clutch type	Multi-plate clutches (forward / reverse)
Gears	forward
Factory code	01J

What’s included

Contents of the 01J mechatronic assembly

The mechatronic assembly combines the hydraulic control unit and the electronic control unit in one housing. A replacement unit is supplied complete, ready to be fitted and adapted to the vehicle.

Hydraulic control unit

Valve body, solenoids and the pressure regulation that operate the clutches and control elements.

Electronic control unit

The transmission control unit and its sensors, integrated with the hydraulic side in one assembly.

Actuators and sensors

The solenoids, speed sensors and position sensors that let the control unit operate and monitor the transmission.

Housing and connector

The machined housing and the electrical connector through which the unit communicates with the vehicle.

Replacement vs exchange

Two ways to source the 01J unit

Both options are agreed manually by email. There is no automated core deposit and no online payment.

Replacement unit. You receive a mechatronic assembly and keep your original unit. The simplest option when the original is not serviceable or not required back.
Exchange unit. You receive a unit and return your original. Exchange is agreed by email and is marked on the quotation request form.
Fitment and adaptation. The replacement unit is adapted to the vehicle after fitting, which requires a suitable diagnostic tool. This is confirmed in the quotation reply.

Technical references

01J fault codes and repair information

The fault codes and repair pages for this family help confirm which unit is required before you order.

Code	Description	Category	Status
P0700	Transmission control system — malfunction (MIL request)	Transmission control	Review
Description The 01J transmission control unit stores P0700 when it detects the following condition: Transmission control system — malfunction (MIL request). A general transmission control fault: the control unit has detected a malfunction in the transmission system that is not tied to one specific component. Codes stored at the same time usually point to the actual cause. A stored code does not by itself prove that a part has failed. Before replacing anything, check the live data, wiring, connectors, power supply and fluid condition, and confirm the fault on the vehicle. Symptoms Emergency mode Harsh or missing shifts Transmission warning light Possible causes Faults stored in other categories at the same time Power supply or wiring problem Mechatronic unit fault Transmission: 01J Category: Transmission control Status: Documented — review advised Related components: Transmission control unit (TCU) · Mechatronic unit This code is documented but not independently confirmed. Confirm it against the specific vehicle before ordering any part. Open full detail Request a 01J quote 01J repair
P0715	Input/turbine speed sensor A — circuit	Speed sensor	Review
Description The 01J transmission control unit stores P0715 when it detects the following condition: Input/turbine speed sensor A — circuit. The fault concerns a speed signal. The control unit needs the input (clutch/turbine) and output shaft speeds to control shifts and clutch slip, and stores the code when a signal is missing, implausible or electrically faulty. A stored code does not by itself prove that a part has failed. Before replacing anything, check the live data, wiring, connectors, power supply and fluid condition, and confirm the fault on the vehicle. Symptoms Harsh or badly timed shifts Emergency mode Incorrect gear or speed display Transmission warning light Possible causes Faulty speed sensor in the mechatronic unit Wiring or connector fault Metal debris on the sensor or sender wheel Fault in the control electronics Transmission: 01J Category: Speed sensor Status: Documented — review advised Related components: Input speed sensor · Output speed sensor · Mechatronic unit This code is documented but not independently confirmed. Confirm it against the specific vehicle before ordering any part. Open full detail Request a 01J quote 01J repair
P0716	Input/turbine speed sensor A — range/performance	Speed sensor	Review
Description The 01J transmission control unit stores P0716 when it detects the following condition: Input/turbine speed sensor A — range/performance. The fault concerns a speed signal. The control unit needs the input (clutch/turbine) and output shaft speeds to control shifts and clutch slip, and stores the code when a signal is missing, implausible or electrically faulty. A stored code does not by itself prove that a part has failed. Before replacing anything, check the live data, wiring, connectors, power supply and fluid condition, and confirm the fault on the vehicle. Symptoms Harsh or badly timed shifts Emergency mode Incorrect gear or speed display Transmission warning light Possible causes Faulty speed sensor in the mechatronic unit Wiring or connector fault Metal debris on the sensor or sender wheel Fault in the control electronics Transmission: 01J Category: Speed sensor Status: Documented — review advised Related components: Input speed sensor · Output speed sensor · Mechatronic unit This code is documented but not independently confirmed. Confirm it against the specific vehicle before ordering any part. Open full detail Request a 01J quote 01J repair
P0720	Output speed sensor — circuit	Speed sensor	Review
Description The 01J transmission control unit stores P0720 when it detects the following condition: Output speed sensor — circuit. The fault concerns a speed signal. The control unit needs the input (clutch/turbine) and output shaft speeds to control shifts and clutch slip, and stores the code when a signal is missing, implausible or electrically faulty. A stored code does not by itself prove that a part has failed. Before replacing anything, check the live data, wiring, connectors, power supply and fluid condition, and confirm the fault on the vehicle. Symptoms Harsh or badly timed shifts Emergency mode Incorrect gear or speed display Transmission warning light Possible causes Faulty speed sensor in the mechatronic unit Wiring or connector fault Metal debris on the sensor or sender wheel Fault in the control electronics Transmission: 01J Category: Speed sensor Status: Documented — review advised Related components: Input speed sensor · Output speed sensor · Mechatronic unit This code is documented but not independently confirmed. Confirm it against the specific vehicle before ordering any part. Open full detail Request a 01J quote 01J repair
P0721	Output speed sensor — range/performance	Speed sensor	Review
Description The 01J transmission control unit stores P0721 when it detects the following condition: Output speed sensor — range/performance. The fault concerns a speed signal. The control unit needs the input (clutch/turbine) and output shaft speeds to control shifts and clutch slip, and stores the code when a signal is missing, implausible or electrically faulty. A stored code does not by itself prove that a part has failed. Before replacing anything, check the live data, wiring, connectors, power supply and fluid condition, and confirm the fault on the vehicle. Symptoms Harsh or badly timed shifts Emergency mode Incorrect gear or speed display Transmission warning light Possible causes Faulty speed sensor in the mechatronic unit Wiring or connector fault Metal debris on the sensor or sender wheel Fault in the control electronics Transmission: 01J Category: Speed sensor Status: Documented — review advised Related components: Input speed sensor · Output speed sensor · Mechatronic unit This code is documented but not independently confirmed. Confirm it against the specific vehicle before ordering any part. Open full detail Request a 01J quote 01J repair
P0730	Incorrect gear ratio	Gear ratio / gear loss	Review
Description The 01J transmission control unit stores P0730 when it detects the following condition: Incorrect gear ratio. This is a mechanical plausibility check: the control unit compares the input and output shaft speeds with the ratio expected for the selected gear. The code is stored when the calculated ratio does not match or a gear drops out unexpectedly. A stored code does not by itself prove that a part has failed. Before replacing anything, check the live data, wiring, connectors, power supply and fluid condition, and confirm the fault on the vehicle. Symptoms Engine revs flare without acceleration Gear drops out or the transmission stays in one gear Emergency mode Transmission warning light Possible causes Clutch or brake slip inside the transmission Hydraulic pressure fault in the mechatronic unit Faulty input or output speed sensor Internal mechanical damage Transmission: 01J Category: Gear ratio / gear loss Status: Documented — review advised Related components: Speed sensors · Clutches / brakes · Mechatronic unit · Gear set or variator This code is documented but not independently confirmed. Confirm it against the specific vehicle before ordering any part. Open full detail Request a 01J quote 01J repair
P0746	Pressure control solenoid A — performance or stuck off	Valve / solenoid electrical	Review
Description The 01J transmission control unit stores P0746 when it detects the following condition: Pressure control solenoid A — performance or stuck off. The fault is electrical: the control unit monitors the current and resistance of each solenoid and pressure control valve, and stores the code when it detects an open circuit, a short circuit or a control current outside the expected range. A stored code does not by itself prove that a part has failed. Before replacing anything, check the live data, wiring, connectors, power supply and fluid condition, and confirm the fault on the vehicle. Symptoms Harsh or missing gear changes Some gears unavailable Emergency mode, often with only certain gears Transmission warning light Possible causes Faulty solenoid or pressure control valve coil Damaged internal wiring or connector in the mechatronic unit Fault in the valve driver stage of the control electronics Contaminated transmission fluid affecting valve operation Transmission: 01J Category: Valve / solenoid electrical Status: Documented — review advised Related components: Solenoid / pressure control valve · Mechatronic valve body · Transmission control unit (TCU) This code is documented but not independently confirmed. Confirm it against the specific vehicle before ordering any part. Open full detail Request a 01J quote 01J repair
P0841	Transmission fluid pressure sensor/switch A — range/performance	Pressure sensor	Review
Description The 01J transmission control unit stores P0841 when it detects the following condition: Transmission fluid pressure sensor/switch A — range/performance. The fault concerns a pressure sensor or pressure switch in the transmission. The control unit uses these signals for clutch and system pressure control, and stores the code when the signal is out of range, too low or implausible. A stored code does not by itself prove that a part has failed. Before replacing anything, check the live data, wiring, connectors, power supply and fluid condition, and confirm the fault on the vehicle. Symptoms Harsh engagement or judder Emergency mode Pump running unusually Transmission warning light Possible causes Faulty pressure sensor Wiring or connector fault A real hydraulic pressure problem Fault in the control electronics Transmission: 01J Category: Pressure sensor Status: Documented — review advised Related components: Pressure sensor · Mechatronic unit This code is documented but not independently confirmed. Confirm it against the specific vehicle before ordering any part. Open full detail Request a 01J quote 01J repair
P0868	Transmission fluid pressure low	Hydraulic pressure	Review
Description The 01J transmission control unit stores P0868 when it detects the following condition: Transmission fluid pressure low. The fault concerns the hydraulic supply of the mechatronic unit. The control unit compares the required system pressure with the measured pressure and stores the code when the pressure is too low, too high, builds up too slowly, or the pump runs outside its normal operating time. A stored code does not by itself prove that a part has failed. Before replacing anything, check the live data, wiring, connectors, power supply and fluid condition, and confirm the fault on the vehicle. Symptoms Delayed gear engagement or loss of drive Pump running unusually often or for a long time Emergency mode or no drive in gear Transmission warning light Possible causes Internal hydraulic leakage (valve body, seals, accumulator) Faulty hydraulic pump or pump motor Low or contaminated transmission fluid Faulty pressure sensor or pressure control valve Transmission: 01J Category: Hydraulic pressure Status: Documented — review advised Related components: Hydraulic pump / pump motor · Pressure accumulator · Mechatronic valve body This code is documented but not independently confirmed. Confirm it against the specific vehicle before ordering any part. Open full detail Request a 01J quote 01J repair
U0101	Lost communication with transmission control module (TCM)	Communication	Review
Description The 01J transmission control unit stores U0101 when it detects the following condition: Lost communication with transmission control module (TCM). The fault concerns data communication between the transmission control unit and other control units on the powertrain CAN bus. The code is stored when messages are missing or corrupted, or the bus hardware reports an error. A stored code does not by itself prove that a part has failed. Before replacing anything, check the live data, wiring, connectors, power supply and fluid condition, and confirm the fault on the vehicle. Symptoms Gear display missing or flashing Emergency mode Several control units reporting communication faults Transmission not reachable with the diagnostic tester Possible causes Wiring or connector fault on the CAN bus Power supply or ground fault at the control unit Faulty transmission control unit Fault in another control unit on the same bus Transmission: 01J Category: Communication Status: Documented — review advised Related components: Powertrain CAN bus · Transmission control unit (TCU) · Connectors and wiring This code is documented but not independently confirmed. Confirm it against the specific vehicle before ordering any part. Open full detail Request a 01J quote 01J repair

All 01J fault codes →

Price & exchange

01J mechatronic unit

Prices are confirmed per request, because the correct unit depends on the transmission generation and the vehicle.

01J Exchange available

01J Multitronic mechatronic unit — 4B0910155B

Refurbished mechatronic unit for the 01J Multitronic (Multitronic CVT), OEM part number 4B0910155B (4B0 910 155 B). Supplied as a complete assembly with the integrated control electronics.

Replacement unit EUR 480.00