Ford HF35 eCVT Gearbox Repair – Mondeo / Fusion / C-Max Hybrid
The HF35 eCVT is a hybrid power-split transmission built by Ford since 2013 and fitted to the Ford Mondeo Hybrid, Fusion Hybrid and C-Max Hybrid (including the plug-in Energi versions) and the Lincoln MKZ Hybrid. It combines a 2.0L Atkinson engine with two motor-generators, MG1 (generator) and MG2 (traction motor), through a planetary gear set — there is no conventional torque converter and no physical gear ratios. It runs on Mercon LV fluid (around 4.5 l). The most common failure is worn differential and transfer shaft bearings on 2013–2015 cars, heard as a grinding noise that grows louder with road speed.
We specialise in HF35 repairs: differential and transfer shaft bearing replacement, rebuilds after an oil leak, and hybrid system diagnostics with P0A code readouts. Contrary to the common view, the HF35/HF45 can be rebuilt, and for far less than a main dealer replacement.
Repair example: Ford Mondeo Hybrid
Patient: Ford Mondeo Hybrid 2.0 iVCT
Symptoms: Oil leaking from the gearbox, excessive play in the differential on the driveshaft side
Repair: All bearings replaced, new seals, play reset to spec
Repair photos
What is the HF35 eCVT gearbox?
The HF35 is the third generation of Ford's hybrid power-split transmission, and the first hybrid transmission Ford built in-house (earlier generations were produced in Japan). Its key features:
- Two electric machines – a generator (MG1) and a traction motor (MG2) integrated into the transmission
- Planetary gear set – a power-split device that divides torque between the motors
- 2.0L Atkinson engine – 143 hp, which with the 35 kW electric motor gives 187 hp in total
- Lithium-ion battery – 1.4 kWh on the Hybrid versions, larger on the Energi (plug-in) versions
- Energy recuperation – recovers up to 90% of the energy released under braking
- Mercon LV fluid – 4.5 litre capacity, change recommended every 60,000 km (the fluid lubricates the bearings, and worn fluid speeds up their wear)
HF35 vs HF45
The HF45 fitted to the Ford Maverick Hybrid is a modified HF35 with an upgraded cooler for the higher loads of towing. Both transmissions share a similar design and the same bearing problems.
Supported models with HF35
Ford
- Ford Mondeo Hybrid – 2014-2022, 2.0 iVCT Atkinson
- Ford Fusion Hybrid – 2013-2020, 2.0L Atkinson
- Ford Fusion Energi – 2013-2020, plug-in hybrid
- Ford C-Max Hybrid – 2013-2018, 2.0L Atkinson
- Ford C-Max Energi – 2013-2018, plug-in hybrid
Lincoln / Other
- Lincoln MKZ Hybrid – 2013-2020, 2.0L Atkinson
- Ford Maverick Hybrid – 2022+, HF45 (related)
Common HF35 gearbox faults
The HF35 is generally reliable, but it has a few known weak points, above all on cars built between 2013 and 2015:
The most common HF35 failure. It shows up as a grinding or thumping noise from the gearbox area, above all while driving. Ford issued a TSB (Technical Service Bulletin) covering this problem.
- The noise grows louder with road speed
- Vibration felt through the floor
- A possible oil leak
An oil leak often goes hand in hand with bearing problems, or follows worn seals. It can lead to overheating and further damage.
- Oil patches under the car
- A falling fluid level
- A warning on the dashboard
The bearing that sits under the generator rotor can wear out, causing noise and vibration whenever the combustion engine is running.
- Noise while the combustion engine runs
- No symptoms on electric drive
- Requires removing the generator
Problems with the electronics controlling the hybrid system are less common. They tend to show up as fault codes and limp mode.
- "Stop Safely Now" messages
- Limp mode
- Fault codes P07XX, P17XX
Fault codes linked to the HF35
Hybrid e-CVT transmissions use fault codes from the P0Axx group, which cover the inverters, generators (MG1), drive motors (MG2) and energy management. These codes are often classed as critical and can force the car into "Stop Safely Now" mode:
| Fault code | Description |
|---|---|
P0A0F | Engine Failed to Start – the engine will not start (MG1 cannot turn the crankshaft) |
P0A1A | Generator Control Module – the generator processor in the inverter failed its self-test |
P0A1B | Drive Motor A Control Module – a fault in the control of the MG2 drive motor |
P0A3E | Generator Inverter Over Temperature – the inverter is overheating (water pump failure or a low coolant level) |
P0A78 | Drive Motor A Inverter Performance – current anomalies on the MG2 drive motor |
P0A7A | Generator Inverter Performance – the MG1 inverter section is not holding its current values |
P0A90 | Drive Motor A Performance – incorrect output from the drive motor or the damper |
P0A92 | Hybrid Generator Performance – MG1 is producing too little energy for its speed |
P0A94 | DC/DC Converter Performance – failure of the voltage converter (it replaces the alternator) |
P0A7B | Battery Energy Control Module – a signal from the BMS reporting an anomaly in the HV battery pack |
Important for Ford Hybrid owners
The HF35 has no torque converter – it is a planetary transmission driven by the MG1 (generator) and MG2 (drive motor) electric machines. The main cause of mechanical failure is worn bearings, usually the result of fluid changes left far too long.
Note: Many hybrid faults (P0A1A, P0A1B) come from a weak 12V battery or corroded earth points. Before paying for inverter diagnostics, check the auxiliary battery voltage (it should read >12.4V).
Our HF35 repair services
1. Differential and transfer shaft bearing replacement
The core repair, covering the parts that fail most often:
- Gearbox removal – the whole assembly has to come out of the car
- Stripping the differential section – inspection and play measurement
- Bearing replacement – new differential and transfer shaft bearings
- New seals – oil seals and gaskets
- Play adjustment – setting the correct axial play
2. Full HF35 rebuild
A comprehensive repair covering every critical part of the transmission:
- Replacing every bearing (differential, transfer shaft, planetary)
- Inspecting the gears and the planetary gear set
- Checking the condition of the electric machines (generator and traction motor)
- Replacing every seal and O-ring
- Leak testing and quality control
3. Diagnostics and repair after a failure
If the gearbox has suffered a more serious failure (a seizure or mechanical damage):
- Full diagnosis of the extent of the damage
- A quote for repairing or replacing the parts
- We can supply the replacement parts
- Repair or reconditioning of the damaged parts
Ford gearbox repair – the HF35 and the other automatics
The HF35 is one of several families of automatic gearbox at Ford. To rule out a diagnostic mistake we always confirm the designation from the VIN and the control unit codes — different gearboxes call for completely different procedures:
- HF35 eCVT (hybrid) — Mondeo / Fusion / C-Max / MKZ Hybrid. P0A… codes, no torque converter, no physical gear ratios. The repair is typically the differential and transfer shaft bearings (see above).
- PowerShift 6DCT450 / MPS6 (wet) — Mondeo, S-Max, Galaxy and Kuga with the 2.0 TDCi diesel. A dual-clutch unit, with mechatronic and K1/K2 clutch problems. See the page on Ford PowerShift 6DCT450 repair.
- PowerShift DPS6 (dry) — Fiesta, Focus, B-Max. The classic symptoms of jerking and oil leaking from the clutch module, codes P07A5 / P2789. Procedurally close to the Renault EDC.
- 6F35 (conventional automatic) — selected Fusion and Escape models. A hydraulic gearbox with a torque converter, so the diagnostic logic differs from the dual-clutch units.
- 10R80 (10-speed) — Mustang, F-150, Ranger Raptor. Rarely seen in Europe.
For most Ford owners in Poland the real choice is between the Ford brand page (a general overview) and the page for the specific gearbox model. We also carry out control unit adaptation after a fluid change and dynamic fluid changes — the latter is what we recommend for the routine servicing of an HF35 or a wet PowerShift.
Why choose us?
- Hybrid specialists – experience with Ford HF35/HF45 drivetrains
- Full rebuild – bearing and seal replacement, electric machine diagnostics
- Original parts – good-quality bearing kits and seals
- Hybrid diagnostics – fault code readouts, electric machine testing
- Competitive prices – far cheaper than a Ford main dealer
- Warranty on the repair – the assurance of a job done properly
How the service works
- Technical consultation – we go through the symptoms, the vehicle history and an initial diagnosis
- Bringing the car in – the repair needs the whole car – we do not take gearboxes on their own
- Gearbox removal – taking out the whole drive unit together with the electric machines
- Stripping and diagnosis – inspecting the bearings, gears, seals and electric machines
- Parts replacement – fitting new bearings, seals and any other parts needed
- Assembly and testing – rebuilding the gearbox, leak testing, quality control
- Refitting in the car – installing the gearbox and reconnecting every system
- Adaptation and road test – adaptation reset, hybrid system calibration, road test
HF35 gearbox repair pricing
| Service | Description | Turnaround time |
|---|---|---|
| HF35 diagnostics | Reading fault codes, external inspection | Free with a booked repair |
| Differential bearing replacement | Diff + transfer shaft bearings | 48-72h |
| Seal replacement | A complete set of seals and oil seals | 48-72h |
| Full HF35 rebuild | Bearings, seals, transmission inspection | 72-96h |
| Repair after a bearing failure | Depending on the extent of the damage | Quoted individually |
* Exact quote after diagnosis. The price depends on the extent of the damage and the parts needed.
For workshops and garages
We work with workshops and car service centres. We offer attractive terms for regular partners. Get in touch for details on B2B cooperation!
Get in touch
Hearing noises from the gearbox? Seeing an oil leak? Showing hybrid system fault codes? Get in touch to talk the problem through and get a quote for repairing your HF35 gearbox.
We also repair other gearboxes
Frequently asked questions
What is the HF35 eCVT gearbox in a Ford?
The HF35 is a hybrid eCVT (electronically controlled Continuously Variable Transmission) developed and built by Ford since 2013. It combines a 2.0L Atkinson engine with two motor-generators, MG1 (generator) and MG2 (traction motor), through a power-split planetary gear set. Unlike a conventional automatic gearbox, the HF35 has no torque converter and no physical gear ratios — power is transmitted through the planetary gear set, and the combustion engine's speed is controlled by the MG1 generator. It is fitted to the Ford Mondeo Hybrid (2014–2022), Fusion Hybrid/Energi (2013–2020), C-Max Hybrid/Energi (2013–2018) and Lincoln MKZ Hybrid (2013–2020).
What are the most common HF35 gearbox faults?
The most common HF35 problems are failed differential and transfer shaft bearings, oil leaking past the seals, a grinding or thumping noise from the transmission, and a failed planetary bearing under the generator. The 2013-2015 model years were especially prone to these faults.
Which fault codes point to HF35 gearbox problems?
The typical fault codes are P0A3E (inverter overheating), P0A78/P0A7A (inverter current anomalies), P0A90 (drive motor performance), P0A92 (generator performance) and P0A94 (DC/DC converter failure). Bear in mind that the HF35 gearbox has no torque converter and no conventional gear ratios – it is a planetary transmission driven by electric machines.
Can an HF35 gearbox be rebuilt?
Yes. Contrary to the common view, the HF35/HF45 can be stripped and rebuilt. Bearing kits, seals and replacement parts are all available. A rebuild costs considerably less than fitting a reconditioned gearbox from Ford.
Which fluid does the HF35 gearbox take?
The HF35 gearbox takes Mercon LV fluid, and the capacity is around 4.5 litres. We recommend changing the fluid every 60,000 km: it lubricates the bearings inside the transmission, and once it is worn it loses its lubricating properties and accelerates bearing wear, which is the leading cause of HF35 failures.
How much does an HF35 gearbox repair cost on a Ford Mondeo Hybrid?
The cost of an HF35 gearbox repair is quoted individually, once the extent of the damage has been diagnosed. The basic scope of work (replacing the differential and transfer shaft bearings plus a full set of seals) means removing the entire drive unit with its electric machines and splitting the housing — typically 48–72h of purely mechanical work. A repair after the planetary bearing under the generator has failed costs considerably more, because the MG1 rotor itself has to come out. Every quote is presented before work starts, and our prices are clearly below a Ford main dealer, which normally replaces the whole gearbox.
Do you repair Ford gearboxes other than the HF35, including conventional automatics and PowerShift?
Yes. We repair the hybrid HF35 eCVT (Mondeo/Fusion/C-Max Hybrid), the dual-clutch PowerShift 6DCT450/MPS6 (Mondeo, S-Max, Galaxy and Kuga with diesel engines) and other Ford automatics. Ford uses several families of automatic gearbox, so the scope of a repair depends on the designation of the specific unit. After reading the codes and reviewing the vehicle history we confirm whether the car has a hybrid HF35 (P0A… codes), a dry dual-clutch PowerShift DPS6, a wet 6DCT450 or a conventional 6F35.
How does Ford's eCVT (HF35) differ from a conventional belt-driven CVT?
Despite the CVT in its name, the HF35 eCVT has no steel belt and no belt-and-pulley variator of the kind used in a conventional CVT (the Jatco JF015E in Renaults, for example) – the ratio change is handled by a planetary gear set. The HF35 is a power-split transmission: the combustion engine and two electric machines are joined to a planetary gear set, and the ratio is varied electronically by controlling the speed of the MG1 generator. That means the HF35 avoids the belt wear typical of a CVT — but it has a failure class of its own, tied to the bearings in the planetary gear set and on the transfer shaft.
Does a grinding or thumping noise from an HF35 mean the whole gearbox has to be replaced?
No. A grinding or thumping noise from an HF35 that grows louder with road speed is the classic symptom of worn differential and transfer shaft bearings — a known fault documented in a Ford Technical Service Bulletin. The repair replaces those specific bearings and seals, without replacing the planetary gear set or the electric machines. What matters is starting the repair before metal debris from the worn bearing damages the gears or the gearbox housing, because the scope of work then grows.