Carbon buildup or sludge on the throttle plate and bore preventing smooth spring return; Worn or sticking throttle body internal return spring or gear mechanism; Throttle body motor winding degradation causing excessive current draw during the spring test; Corroded or chafed wiring in the throttle body harness connector or pins; Failed throttle position sensor (TPS) inside the throttle body giving implausible feedback during adaptation; Low battery voltage or poor ground causing the DME to abort the adaptation test; DME software calibration issue requiring a software update or adaptation reset

DTC codes / BMW codes / P1634

P1634 · BMWThrottle Valve Adaptation Spring Test Failed

Q: What does code P1634 mean?

Throttle Valve Adaptation Spring Test Failed. P1634 on BMW vehicles means the engine control module (DME) commanded the electronic throttle valve through its full spring-return test and the measured response did not match the expected adaptation values. The computer detected that the throttle plate did not return to its default limp-home position within the expected time or current draw during the spring test, so it flags the adaptation as failed.

P1634 on BMW vehicles means the engine control module (DME) commanded the electronic throttle valve through its full spring-return test and the measured response did not match the expected adaptation values. The computer detected that the throttle plate did not return to its default limp-home position within the expected time or current draw during the spring test, so it flags the adaptation as failed.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyIntermediate

AreaComputer and output circuits

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms besides the warning light
Reduced engine power or limp-home mode with a message on the iDrive or instrument cluster
A throttle pedal that feels unresponsive or delayed during the first few presses after startup
Rough or fluctuating idle as the DME struggles to hold a stable throttle opening
Intermittent hesitation or a sudden drop in power when accelerating from a stop
A stored fault that returns immediately after clearing if the throttle body is mechanically binding

Common causes, most likely first

Carbon buildup or sludge on the throttle plate and bore preventing smooth spring return
Worn or sticking throttle body internal return spring or gear mechanism
Throttle body motor winding degradation causing excessive current draw during the spring test
Corroded or chafed wiring in the throttle body harness connector or pins
Failed throttle position sensor (TPS) inside the throttle body giving implausible feedback during adaptation
Low battery voltage or poor ground causing the DME to abort the adaptation test
DME software calibration issue requiring a software update or adaptation reset

How to diagnose and fix it

Read all stored and pending fault codes with a BMW-capable scan tool and record freeze-frame data before clearing anything
Check battery voltage and charging system output, then clear adaptations and rerun the throttle spring test
Remove the intake boot and inspect the throttle bore and plate for carbon; clean with throttle-body cleaner and a soft brush
Back-probe the throttle body connector and check for corrosion, pushed pins, and continuity to the DME
Command the throttle plate through its full range with the scan tool and watch for binding or a current spike
If cleaning and wiring checks pass, replace the electronic throttle body and perform the adaptation relearn procedure
After repair, clear codes, run the throttle adaptation test, and verify no pending faults return during a road test

Why throttle adaptation fails after cleaning

A throttle body that was cleaned but not re-adapted will often set P1634 because the DME still holds the old carbon-compensated learned values and rejects the new spring-return timing.
A weak battery is a common missed cause: the DME aborts the spring test if system voltage drops during the sweep, so the code appears even though the throttle body is healthy.
P1634 does not always mean the throttle body is bad; a chafed harness section near the intake manifold can intermittently short the motor circuit and mimic a mechanical spring fault.
On some BMW engines a failing accelerator pedal position sensor sets a companion code that triggers the same adaptation failure, so always check pedal codes before replacing the throttle body.
After replacing the throttle body, the adaptation must be run with the engine off and the key on, and the test will fail again if the battery charger is not connected during the procedure.

Can I keep driving with P1634?

You can usually drive the car to a workshop, but expect reduced power and possible limp-home mode, so avoid hard acceleration and highway merging until the fault is repaired. If the throttle feels stuck or the engine surges, stop driving and have the vehicle towed.

Tools that help

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Guidance is general and written for BMW vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.