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Slow Down Light

I’ve been having this new problem with my F430 lately.  I have been getting a Slow Down light and the car gets stuck in gear and will not shift.  This has been happing more and more.

Started late in March when on the track.  Then I did a run of 5 track days in a row at Thunderhill Raceway Park late April and after a few laps at speed it would get a solid Slow Down light and stuck in gear.  Most times it would come back to normal after a few corners and I would pit.  One time it had a clunking like sound and I stopped in the bypass of turn 5.  At the end of that session it started and seemed fine as I once again returned to the pits.  Later laps I reduced the RPMs to no more than 7,000 and I would get a few laps in before the problem happened.  By the end that 5 day stint at the track I was down to half a lap before the problem would occur.  On the street it doesn’t ever have this problem.

I’ve had some issues with the exhaust on this car.  Late last year I put my Tubi exhaust on the car as it appeared my old stock muffler was blowing white powder over the engine.  Looked to be the headers and they were replaced last year also.

After this new problem started happening I also managed to have the Tubi tips on the left side break off on track.  So I put the old stock exhaust pipes and a different center stock muffler I got from Jesse and installed that.  I also replaced the thermocouples and rear O2 sensors.

When all this was happening I noticed that the left side of the that different center stock muffler seemed like it was torched (see picture below).  And the usual white ash on the the inter tail pipe when running on the track appeared on the right side but not the left (also see photo below).

So with all this I’m thinking maybe some how the left side is not working correctly and heat is getting backed up into the system and eventually the thermocouple gets triggered and the solid Slow Down light happens.

I have seen flashing Slow Down lights on hot days at the end of a track day before.  But never a solid Slow Down light and the car stuck in gear.  And these were cool days by Thunderhill standards.

Finally I did get a nice take off F430 stock muffler and pipes which are on the car now.  Did a few touring laps at Laguna on the Ferrari Challenge weekend running a bit high RPMs with no issues, but that is not much of a test.  We’ll see what the next track day brings.

Any thoughts on what can  an F430 Slow Down light and the car to be stuck in gear?


The complexities of these cars can be intimidating and quite frustrating at times!  It takes years of experience and training to diagnose the technology that keeps Ferrari so respected and exhilarating.  And I find it so fun and important to have a basic understanding of what’s going on with each click, buzz, and whine while out on the open road or all-out hustling around the track.

For decades Ferrari has used exhaust temperature sensors known as thermocouples to monitor engine performance and catalytic converter safety.  Threaded into the exhaust are thermocouple probes that don’t look too different to the probes used in your oven for that prime rib roast or turkey.  They are wired to thermocouple ECUs.  The ECUs translate the thermocouple analogue signal into a warning light on the dash.  Or, on later cars the signal is converted for the main engine motronics to read and interpret.  The exhaust temperature is a great way to monitor engine efficiency from a basic safety point.  An engine running without enough fuel (lean) can get extremely hot and damage itself.  An engine with too much fuel (rich) or misfiring (passing unburned fuel to the exhaust) with start to overheat the catalytic converters.  Too far advanced ignition timing can cause engine damage through pre-detonation.  A precursor to the damage is hot exhaust.  So, this is a reliable system to get the driver to pull over or “slow down” to protect the engine.  When the exhaust starts overheating the dash will indicate to the driver a “slow down” light.  On late cars a slow-down light can be accompanied with engine torque reduction.  As most Ferrari owners know, the engines and cats have been far more reliable than the individual components of the thermocouple systems.  Most slow down lights that I have encountered are due to a failing thermocouple or thermocouple ECU rather than a cat failing or engine malfunctions.

The F430 introduced an all-new powertrain system known as “E-Diff”, standing for electronic differential.  The system takes what we know as a standard limited slip differential that was automatically and mechanically controlled and takes full control through hydraulic pressure with electronic modulation.  This E-diff (like most things Ferrari) takes traction control to all new heights.  With the introduction of the E-Diff also came the steering wheel manateno.  The pilot could choose between different settings of electronic intervention for ABS, throttle, and traction control to meet road conditions and driver skill.  

The reason E-Diff is being discussed in a slow-down/thermocouple article is because Ferrari hydraulically tied this to another vital system on these cars: the F1 gearbox.  E-Diff shares the F1 reservoir, pump, accumulator, and valve block.  On a gated shift F430 these components are present solely to run E-Diff.  The combined demands of an active differential clutch, gearbox clutch, and automated shifting hydraulics can sometimes overcome the F1 system pump and accumulator.  Instead of creating yet another driver warning, Ferrari alerts the driver to cool-it with the slow-down light.  If there is an outright failure with a sensor there are other failure lamps that will come on along with some sort of limp mode.

Any developing issue with the E-Diff will first manifest with the slow-down light and start storing faults in the sand-alone E-Diff module and/or the gearbox module.  Our reader’s symptom of not being able to shift gears is the determining factor to start looking at the E-Diff for the cause of their slow-down light.  The fact that gears become unavailable leads to reason that the F1 pump is unable to keep up the track demands of gear shifts and E-Diff use.

Our scan tool would be able to hook up to the car and read stored and live data.  Aside from stored faults to guide our diagnosis, we’d be looking at gearbox parameters such as F1 pump run time and base pressure.  Just opening the door on an F430 will tell me much about the health of the F1 pump and related system.  The pump is programmed to run to prime the F1 system upon door opening to apply the clutch and achieve neutral for start-up.  A weak sounding pump or one that runs too long can be indicative of a failure.  Ferrari has bulletin **_(FNA29?)_** to monitor pump on-time as a percentage and determine if it is running too much.  An early issue while I was at the dealer with these cars under warranty were loose bleed screws on the hydraulic actuator.  These would allow internal fluid to bypass and use more circuit flow than needed from the pump.  Another suspected internal issue may be a worn F1 accumulator.  An accumulator that does not hold/maintain pressure anymore can overrun the pump and also start polluting the F1 system with metal.  This metal normally gets caught in one of two filters in the system.  I generally pull these screens and inspect as a first step in the diagnostic process for a pump running problem.  A pump that flat-out won’t run can also cause those symptoms and could easily be identified during the slow-down event with an ear.  The relay would be my first stop in this case.  Pumps that run too long generally wear out prematurely and would be replaced in conjunction with another component as a secondary failure.