Diagnosing the F1 System Pt.1

The F1 system on these cars are relatively complex and have quite a few moving parts that can fail or wear out over time.

Luckily, the TCU on these cars provide a handful of useful parameters that can be used to help pin-point where issue lie. In this post we will look at some of the common failure points, and the corresponding things to investigate. It isn’t intended to be completely comprehensive but rather hints on where to dig further if you are encountering issues.

It’s really handy to have a scan tool capable of reading live data from the TCU to fully diagnose problems. Some can be done through timing of pump activation, but you really want the tool for a full picture. Things like the Launch X431 or even my F1 Param Viewer are suitable tools for this.

External Leaks

Leaks can be indicators of loose fittings or failing seals in the system. Generally, there are two fluids you may find in/around the F1 system. The best way to identify which is which is by appearance (color/smell if quite distinct for either). If you are still running the factory fill of fluid, it’s likely green (CHF11S) for the F1 hydraulic fluid and amber/dark for the gear fluid. F1 fluid doesn’t have much smell to it, whereas gear fluid just plainly smells awful.

The first fluid to look for, gearbox fluid. Gearbox fluid most commonly can migrate from the fork area that the actuator connects to the gearbox and seep past the seals in the actuator either into the potentiometer area or rear cap. If you see gearbox fluid on the area where it mates to the gearbox, chances are you need to simply have the actuator removed and resealed on that surface (it uses a RTV). If you see seapage on either end of the actuator, this is likely more serious and indicates the internal seals are starting to fail. There is a gasket on both of these covers, but it’s purpose is NOT TO seal oil into the system (simply more keeping dust out). Sealing these off may remove the visual apperance of a leak but is just hiding a larger problem.

Unfortunately if seals are leaking badly enough, the actuator itself will need a rebuild or replacement (neither of which are cheap). Leaving it too long can also damage the potentiometers if that cavity fills up and they get immersed in gearbox fluid.

The other common area is on the top of the actuator where the banjo bolts connect to all of the hydraulic lines. If you see leakage here it may be that one of the bolts is loose, but unfortunately I’ve heard of cases where the banjo fitting itself had a hairline crack. Additionally, the hoses themselves could be leaking. The latter two will require replacement of the offending hose. The factory hoses are quite expensive but I’ve heard many people replacing them with aftermarket hoses from a good hydraulic line maker.

Accumulator System

Another area of concern is the accumulators used on the hydraulic system. The accumulators purpose is to store hydraulic pressure in the system. It’s better to run the pump longer, but less frequently.

There are generally two different types of accumulators used in these cars and will vary depending on the model. Bladder (left) and Pistron (right).

Neither is necessarily better than the other and both are prone to failure/wearing out. How they fail differs however.

The bladder type contains a membrane with pressurized nitrogen gas on one side and your hydraulic fluid on the other. These generally fail in the sense that the membrane leaks and the nitrogen mixes with the hydraulic fluid. This is obviously not a good condition as it introduced “air” into the hydraulic loop. When this happens, you may experience erratic pressures and the inability to shift. Although the factory Ferrari part used on some models (247346) is quite expensive, this same accumulator is used on many other vehicles such as the Alfa’s which can be found for under $100. Note when replacing these, you will need to do a entire bleed of the system!

The other type is a piston type. When these fail they tend to go gradually. You’ll notice often the pump priming more regularly, and the on time of the pump reducing. Eventually they wont be able to store enough hydraulic pressure to reliably complete shifts or you’ll run into problems with rapid shift changes. These don’t have a non factory part alternative I am aware of and so can cost more to replace. Again, replacement of this part requires a full bleed of the system.

Solenoid Leaks

Another common place for wear is in the solenoids themselves in the power unit. These solenoids control the hydraulic pressure being fed to the gearbox and clutch actuators in order to move them as desired. By sequencing them appropriately, the TCU can ensure that a gear change request is completed.

There are generally 6 solenoids (additional on say the F430 for the E-Diff) and two main types – PFV and PPV.

Solenoid IDUsageType
EV1, EV2Gear EngagementPPV
EV3, EV4, EV5Gear SelectionPFV

EV is the clutch solenoid and is of the PFV (proportional flow) type. The system can modulate the clutch position by feeding a controlled current through this valve which regulates its flow of hydraulic fluid.

EV1 and EV2 are of the PPV (proportional pressure) type. The are responsible for gear engagement or in other-words meshing and disengaging the gears. They are controlled by a PWM (pulse width) signal from the TCU and feed pressure that’s proportional to the input current.

The remaining valves EV3, EV4, EV5 are also of the PFV type like the clutch. These control the gear selection movement of the actuator. They are effectively used more as on/off (binary) type valves.


If you have problems with certain gear engagements, its often help to look for common solenoids that serve them.

The TCU also continually measures leakage rates of the clutch solenoid (it tends to be the most heavily used and so wears out the quickest). Generally, a healthy solenoid has <30cc/min leakage at room temperature. My personal experience shows once you start approach 60cc/min you may start seeing problems. The X431 scan tool can read these parameters.

Pump, Pump Motor, Pump Relay

Another failure point is around the pump itself. Here, the culprit is often the relay or the pump motor. Luckily, both are fairly easy repairs and by again looking at the Alfa equivalent part, can be done for a lot less.

The relay failure is most often noted by the pump motor never shutting off. This is due to the internal contacts fusing together which prevents the TCU from having control to turn it off when the pressure reaches the set limit. Unfortunately, when you encounter this, it can quickly burn the pump motor out. Some people do preventative maintenance here and replace the relay before it fails because of this and its a fairly low cost part.

Should you find that the pump motor itself has either burnt out or become weak, it can be replaced in-situ on the power unit. If you don’t remove the pump head and simply replace the rearward portion (the motor), you don’t need to bleed the system as the hydraulic circuit never gets opened.

Timing Analysis

One generally easy way to verify the health of your F1 system is to watch how the pump operates. Below if a list of guidelines to look at that may steer you in the right direction. Before taking any corrective actions, its best to verify with other data points (such as a scan tool, etc) as these are meant as a simple guideline only.

The main measurements you can take without a scan tool is to see how the system behaves both with the engine off, and the engine on.

In either case, measure the amount of time between pump running (you can do this by hearing the whirling) over several activation cycles while not touching anything on the car (e.g. performing gear changes, etc). Also measure how long the pump actually runs as well. Using these metrics a lot can be told about the health of the system and serves as a good starting point for diagnostics.

ObservationExpectedPossible CausePossible Resolution
F1 Pump stays on continuouslyRun times <6sStuck F1 RelayReplace Relay
F1 System Doesn’t Prime when opening doorPrimes for some period of timeBurnt pump motorReplace pump motor
Pump on Time LongRun times <6s (except for initial prime on startup)Weak pump motor

High contact resistance
Replace pump motor

Replace Relay
Pump on Too Short of TimeRun times <4sAccumulator LeakyReplace Accumulator
Time between Primes under Two Minutes WITH KEY ON, ENGINE OFFTime Between Primes Over 2 MinutesAccumulator Leaky

Solenoids Leaky
Replace Accumulator

Check Solenoids
Time between Primes under One Minute WITH KEY ON, ENGINE ON, IDLE, but ENGINE OFF test above test passedTime Between Primes Over 1 MinuteAccumulator Leaky

Clutch Solenoid Leaky

Clutch actuator Leaky
Check Listed Components
Clutch Solenoid OFF Leakage >30cc/min<30cc/min at room tempWorn Clutch SolenoidReplace solenoid
Clutch Solenoid ON Leakage >30cc/min<30cc/min at room tempWorn Clutch Solenoid

Clutch actuator Leaky
Check Listed Components
Pump Activation time <1 second>1 secondBad accumulatorReplace Accumulator

Other Faults

There is a myriad of other faults you may encounter that could cause the vehicle to either not start, or stop, or failure to engage gears.

Always start with a scan tool to read any codes from the TCU. Note that you will need a tool specifically for this, as generic OBD tools will NOT read this information. Often this can give a hint as to defective sensors (e.g. clutch position sensors).

Here are some additional troubleshoot areas to review.

ObservationPossible CausePossible Resolution
Gears having difficulty engaging, transmission returning to neutral on its own1. Low fluid level

2. Hydraulic pressure low

3. Selection calibration invalid or incomplete

4. Worn clutch

5. Worn solenoids
1. Confirm F1 fluid level in reservoir

2. Confirm pump operation/leaks/etc. (scan tool). Check bleed screws are tight.

3. Re-run calibration program (scan tool)

4. Repair/replace components

5. Repair/replace components
Engine fails to turnover1. Defective brake pedal switch

2. Defective clutch position sensor

3. Fluid level

1. Repair/replace components

2. Repair/replace components

3. Confirm F1 fluid level in reservoir
Engine stalls when starting off1. Defective clutch position sensor

2. Worn clutch

3. PIS too tight
1. Repair/replace components

2. Repair/replace components

3. Check PIS
Can’t change gears1. Low fluid level

2. Hydraulic pressure low

3. Issue with steering wheel paddle circuit
1. Confirm F1 fluid level in reservoir

2. Confirm pump operation/leaks/etc. (scan tool). Check bleed screws are tight.

3. Verify circuit/components
Car won’t take off even though in gear 1. Sticky thrust bearing

2. Failed clutch solenoid/actuator or circuit
1. Repair/replace components

2. Verify circuit/components

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3 thoughts on “Diagnosing the F1 System Pt.1

Add yours

  1. Very nice article and hydraulic pressure graph – very useful for diagnosing early fault on the F1 system. Question about the F430 F1 hydraulic system when car battery is disconnected for several hours – does the gearbox stay in neutral ? I’m trying to rotate the engine crankshaft manually but too much resistance – was wondering if the clutch and gearbox are re-engaged (if not, next step is to remove the spark plugs). Cheers, Paul


    1. The transmission will be in whatever gear it was when you shut it off. It can’t/won’t be able to shift either into or out of neutral when not powered. The clutch rests in a engaged state, so if you need to rotate it, the only way will be to ensure its neutral when you shut it off.


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