The classic V12 owner's nightmare — and the part that actually fixes it
If you own a BMW E31 8 Series or E32 7 Series with the M70 or S70 V12 engine, you already know that the EML system is the source of nearly every drivability complaint these cars develop with age. Throttle lag. Rough idle. Cold-start hunting. The dreaded EML warning light. Limp-home mode. A bank dropping cylinders and the V12 running, briefly, as a coarse straight-six.
These symptoms have one common root cause: the throttle position encoder inside the DK (Drosselklappe) throttle body assembly is electrically worn out. After 30+ years of duty, the resistive track that tells the EML control unit where the throttle plate is has degraded, the wiper has worn into the surface, and the signal is no longer reliable.
The good news: this is a fixable problem. The bad news: BMW never sold the encoder plate as a separate service part. A new factory throttle unit cost owners nearly $4,000 USD when last available — and they have not been available new for many years.
The practical fix is an upgraded replacement encoder plate, part number 88500013. Below, we'll walk through how to know whether this is your problem, and how to fix it properly.
How the M70 / S70 EML system actually works
The M70 (and its sportier sibling, the S70 in the 850CSi) was BMW's first fully drive-by-wire engine. There is no cable connecting your accelerator pedal to the throttle plates. Instead, the pedal sends a position signal to the EML control module, which then commands two electronic throttle valve assemblies — one per cylinder bank — to open by a corresponding amount.
Each throttle assembly contains:
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A DC motor that physically moves the throttle plate
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A potentiometer-style encoder that reports the plate's actual position back to the EML
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A gear train connecting the two
The encoder is the weak link. It works by sweeping a metal wiper across a printed resistive track. Every time the throttle moves, the wiper scrapes that track. After 100,000+ throttle-cycles over three decades, the wiper has carved a measurable groove into the resistive surface, and the resistance values it returns are no longer linear or repeatable.
The EML control unit notices that the commanded position and the reported position don't match — and lights the EML warning, often dropping the affected bank out of operation as a safety measure. This is exactly what owners experience as the bank shutting down and the engine running on six cylinders.
The diagnostic clues — is it really the encoder?
These are the symptoms that point specifically to encoder failure, rather than other M70 issues like fuel delivery, cylinder identification sensors, or coil packs:
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EML warning light appearing intermittently, often after a hot restart
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Throttle response that feels laggy or 'rubber-band' under part throttle
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Rough or hunting idle, especially cold
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Occasional EML codes 1216 (throttle potentiometer) or related throttle fault codes
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One bank cutting out under load while the other continues normally
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The car going into limp-home mode and then recovering after a key cycle
Quick test: With the car off and the throttle harness disconnected, you can measure the resistance across the encoder pins while slowly opening the throttle by hand. A healthy encoder shows a smooth, monotonic change. A failed one shows jumps, dropouts, or dead spots. Compare with your other bank — if one is smooth and one is not, you've found your problem.
Why used throttle bodies are a false economy
It's tempting to find a used DK throttle assembly on eBay or in a breaker's yard. We strongly advise against it for one simple reason: the encoder inside that used unit has the same wear as yours. You are replacing a 30-year-old worn part with another 30-year-old worn part, and you have no way of knowing which one is worse. Within months, you'll be in limp-home mode again.
Reconditioning the encoder yourself is also a popular forum suggestion. It's a clever stopgap — you can clean the wiper, sometimes reposition it slightly to a less-worn part of the track — but it's a stopgap, not a fix. The track is still worn. You've moved the wear, not solved it.
The proper fix: an upgraded encoder plate
The BMW E31 / E32 V12 Throttle Body Encoder Plate (Part No. 88500013) is a limited-production replacement engineered specifically to solve this. Three things make it different from the original BMW part:
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Premium Japanese resistors replace the original components, providing dramatically better long-term electrical stability
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The encoder surface is specially treated for wear resistance — the very thing that killed the original
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The redesign follows the latest OEM-spec geometry, so it fits the original throttle housing without modification
Each kit ships with a fresh seal set and gasket, so the throttle body can be opened, cleaned, the encoder replaced, and reassembled to a fully sealed condition in a single sitting.
What you can expect after fitting it
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Throttle response returns to the precise, almost telepathic feel the M70 had when new
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Idle becomes smooth and stable across cold and hot starts
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EML warning lights and bank-shutdown events stop
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Driveability is consistent — no more 'is today a good day or a bad day' V12 lottery
Installation overview
This is a workbench job. The throttle assembly needs to come off the car first; we recommend doing both banks even if only one is showing symptoms, because the second one is on borrowed time. Allow a full afternoon.
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Disconnect the battery for at least one hour (this is required by the EML adaptation procedure)
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Remove the throttle body assembly from the cylinder bank
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On the workbench, remove the six Phillips screws holding the motor housing to the throttle body
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Separate the housing and remove the worn encoder plate
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Fit the new encoder plate, refresh the gasket and seal set
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Reassemble, refit to the car, and reconnect
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Perform the EML adaptation procedure to re-sync both banks
EML adaptation procedure: Battery disconnected for at least 1 hour → reconnect → start engine and allow to reach operating temperature without touching the pedal → in first gear, accelerate past 5,000 rpm → release pedal, coast to idle. This re-teaches the EML the new encoder's range.
Frequently asked questions
Will this fit the E32 750i / 750iL and the E31 850i / 850Ci / 850CSi?
Yes. Part number 88500013 is compatible with all M70 throttle bodies (E31 and E32) and the S70 throttle bodies in the 850CSi. The encoder design is shared across all V12 applications of this era.
Do I need to replace both throttle bodies' encoders?
Strictly, no — if only one bank is throwing codes, you only need that side. Practically, yes — the second one is the same age and will fail soon. Many owners do both at once to avoid pulling the intake twice.
Is this truly better than a new BMW part would have been?
Yes. The original BMW encoder was the weak point of an otherwise bulletproof system. Our replacement uses higher-grade Japanese resistors and a treated encoder surface specifically chosen to outlast the OEM design.
How long is the production run?
This is a limited production batch. When the current run sells out, there is no guarantee of further availability — these are not high-volume mass-produced parts. If you have an M70 or S70 car, the time to buy is when stock is available.
Ready to bring your V12 back to life?
Shop the BMW E31 / E32 V12 Throttle Body Encoder Plate — Part No. 88500013 — built with premium Japanese resistors and a treated encoder surface. Fits all M70 and S70 throttle assemblies.
While you're in the rear of an E31, it's also worth inspecting your E31 EU-spec FTP Light Strip Wiring Harness pair and your E31 Lower Ball Joint Bushings — both are common failure points on the platform and both are part of our E31 catalogue.