u/HarryCumpole

This is probably old news, and I can't see anything on their official site, however a track day video I watched on YouTube noted that the year they went (a handful of years back now) they had to "charge" a card or some sort of credit system to purchase things on-site. Is this still a thing, or not?

This is a followup to the adventures that I had with the HV PTC heater in our C350e this winter.

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In short, Mercedes-Benz authorised dealership repair departments opt for replacing the entire unit by default, whether there is a fault with the actual PTC heater or not. This can be the difference between a small and manageable repair that does not involve the HV system at all, or one that requires an entire €3000 unit replacement in addition to the small repairs and associated coolant drain, HV de-energisation, labour hours, etc.

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The HV PTC (positive temperature coefficient) heater in hybrids is a high voltage unit that is designed to provide heating to the cabin in electric-only mode, since without ICE power the coolant loop is unable to heat and defrost the cabin. Safety surrounding this often means that a non-functional PTC heater or any errors surrounding that system will put a car into some level of lockdown as cabin heating is usually a requirement of windscreen visibility, etc.

PTC heaters can fail, especially those in W205 and similar models of the time where the unit was shoehorned into the only place that was readily available; behind the front-right wheel arch cover. This location is not isolated from the elements, so is often exposed to water, dirt and during winter, salty water ice. The arch cover does not adequately provide shielding.

This has been a known issue with the model for a long time, however not enough of an issue that MB considered a recall. Still, an issue. The TIPS document for this follows a maximalist view of "replace everything indiscriminately", even if the issue has nothing to do with integrity, safety or condition of the PTC heater itself.

The heater has two electrical connections and two for the coolant loop; one is the HV supply and the other low-voltage communications. It is the latter of these that threw my issues, and it corresponded directly to whether outdoor and local temperature froze or defrosted salty road slush. At -20C, salty ice is non-conductive. When the PTC heater warms up, that becomes conductive.

It's a known issue via the TIPS bulletin that the low voltage connector's wire sealing plugs that prevent water ingress via each of the connector's wires degrade and fail over time. This is seen as blue-green corrosion on the contact side, eventually causing communication issues and progressively or fully locking down the car's safety systems.

The issue is that Mercedes-Benz do not diagnose the extent of a fault in this system by checking whether a simpler connector-level replacement is an appropriate and economic repair as consumer law advocates. Instead, the recommendation on the basis of it being "an HV system" is that the entire unit is replaced. Even if the PTC heater-side male contact pins are not demonstrated as having corrosion, or there being any water ingress into the system itself.

This is the situation I found myself in, with a lightly-corroded harness-side connector and transferred-only verdigris on the pins. Replacement of the harness connector with new seals, crimped contacts, blanking plugs, etc. as per the TIPS document.

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This is not a complaint, but an observation. Should you find yourself in a situation where the car is locking you out of E-Mode and reporting "Malfunction" in the dash display, this is likely where you are. There's a variety of codes surrounding this one that need reading by XENTRY or whatever, not a surface-level OBDII reader. The bottom line is that you should always ask for an inspection of the connector, and visual evidence of the condition of the heater-side pins. If needs be, order the harness connector repair kit and have a separate repair workshop replace the connector, reset errors, etc. as part of your initial diagnostic. This would need doing anyway. Simply replacing the entire PTC heater whether required or not is excessive.

The mods kindly gave me the go-ahead to share this here.

I’ve written a long-form piece on Fender’s recent German court win concerning the Stratocaster body form, but the article is less about the ruling itself and more about what it may mean for builders, partscasters, small makers, second-hand sellers and platforms like Reverb.

The main point is not that Fender suddenly “owns” every Strat-style guitar. That is not what happened. The concern is the grey area between a narrow court ruling, cease-and-desist pressure, marketplace policy, and how platforms may choose to police listings long before anything is tested properly in court.

I tried to separate confirmed facts from speculation, especially around which companies have reportedly received letters, and to draw a clear line between genuine amateur building, commercial copying and outright counterfeiting.

Interested to hear how other builders read this, especially those who sell occasional instruments, partscasters, replacement bodies, or vintage copies.

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