Subaru Stalling at Idle – Torque Converter Pressure Problem Explained

Subaru drivers know what their vehicles are supposed to feel like. So when your Outback, Legacy, Forester or Tribeca suddenly begins to dip into low revs or even stall when you stop at traffic lights, it’s a red flag. The engine might feel like it’s struggling against something, almost as if you’re stopping a manual car without pressing the clutch. In most cases, it isn’t the engine or ECU at fault. The real issue lies inside the TR690 Continuously Variable Transmission (CVT), specifically in the torque converter.

This isn’t guesswork. Subaru itself released a technical bulletin in January 2014 — Bulletin 16-90-13 — identifying this exact failure pattern. In that document (check the inserted part for your information below), Subaru outlined a common root cause: premature internal wear inside the torque converter that blocks the hydraulic release channel for the lock-up clutch. When this happens, the converter fails to release properly as the car comes to a stop. Instead of letting the engine idle freely, it continues to hold the driveline, dragging the engine down and sometimes stalling it altogether.

January 2014 — Bulletin 16-90-13

“This bulletin announces the availability of a countermeasure torque converter assembly to address
a customer concern of very low engine RPM when coming to a stop. The condition is similar to
coming to a stop in a manual transmission-equipped vehicle without depressing the clutch pedal.
>Thrust washer wear inside the torque converter can cause restriction of the oil passage used to bleed
off lock-up clutch application pressure. The result is either a delayed (momentary low engine rpm)
or no lock-up pressure release. The thrust washer has been changed from a solid bushing-type to a
needle bearing type.
COUNTERMEASURE IN PRODUCTION
The countermeasure torque converter was incorporated into production October 1, 2013 starting with
transmission #633208. Remanufactured CVT assemblies with a production date of 12/31/2013 or
later as indicated on the shipping container label include this revised torque converter.”

Stalling at Idle is mechanical

What’s happening internally is surprisingly mechanical. Inside the torque converter is a component known as a thrust washer. Over time, this washer wears down and begins to deform. As it does, it encroaches on the pressure bleed passage used to disengage the torque converter clutch during coast-down. In some cases, pressure release becomes delayed, and the engine struggles to idle normally. In worse cases, the clutch remains engaged entirely, causing the engine to stall at every stop.

This isn’t just theory. At Brisbane Tuning & Turbo, we’ve repaired a number of these converters and seen both mild and severe symptoms. Some vehicles simply dip to 300–400 RPM briefly before recovering. Others stall cleanly, consistently, and without any warning lights. In every case, the fault traces back to the same internal wear pattern.

How most workshops approach Subaru idle stalling

Most workshops approach Subaru idle stalling or low-RPM issues as if they were engine-related. Often, replacing spark plugs, ignition coils, or even fuel filters in an attempt to smooth out idle. Some go a step further and replace the entire torque converter. Yet they do so with standard reconditioned or second-hand units that are at best simply rebuilt back to the original factory specification, and without addressing the root design flaw. This approach might restore drivability for a short period, but it leaves the original failure mechanism untouched. The result is predictable: the problem often returns even within months.

Subaru itself acknowledged the flaw in Technical Bulletin 16-90-13, which calls for preventative modifications to the torque converter’s internal structure. This bulletin makes it clear that the worn thrust washer inside the converter is the trigger point for the fault. It also makes it clear that unless the internal hydraulic bleed path is preserved under all conditions, the torque converter clutch will continue to drag the engine down as you come to a stop.

This is where Brisbane Tuning & Turbo stands apart. We don’t just replace the converter — we re-engineer it. Every TR690 converter we repair receives a precision-machined internal upgrade, replacing the OEM thrust washer with a high-grade needle roller bearing and preparing the housing to match. This change eliminates the original wear point, protects the bleed passage from blockage, and ensures clean lock-up release at idle. It’s a permanent fix backed by measured data, not a temporary patch. Because we specialise in both torque converter rebuilding and CVT diagnostics, we can confirm post-repair performance with live converter slip data, proving that the upgrade works exactly as intended.

We don’t just replace the washer

At Brisbane Tuning & Turbo, we don’t just replace the washer. We machine the torque converter housing and upgrade the internal hardware, replacing the thrust washer with a precision-fit needle roller bearing. This not only restores proper clutch clearance but ensures the bleed passage remains fully open under all conditions. The needle bearing dramatically reduces friction and wear, permanently fixing the pressure lock-up issue. We’ve applied this method across several TR690 converter builds and validated the results using coast-down RPM logs and converter slip data.

Software update or Flush CVT fluid won’t help

If you’ve been told to update your software or flush your CVT fluid to fix a stalling issue, it’s time to consider a more permanent repair. ECU reflashes won’t remove internal converter debris, and fluid flushes won’t fix hydraulic flow restrictions. The only real solution is mechanical — and that means opening the torque converter and upgrading it properly.

Our Redorq CVT Diagnostic Package includes a full scan, road test, and live logging session to capture converter behaviour. We collect the information we need under real coast-down conditions. We monitor torque converter lock-up command versus actual slip, track idle RPM drops, and cross-reference pressure modulation solenoid responses. This gives us a complete picture of whether the stalling is being caused by clutch hang-up or if there’s a secondary fault in the valve body or solenoids. From there, we can build a repair plan specific to your vehicle’s failure.

We don’t sell Band-Aids

If you’re a Subaru owner experiencing strange low revs at a stop, unexpected stalls, or just want peace of mind before a long trip, we invite you to book a proper diagnosis. We don’t sell Band-Aids. We fix the problem — and we prove it with data.

Call Brisbane Tuning & Turbo or book your CVT stalling diagnosis online today. We’ll get your Subaru back to the driveability you expect — smooth, reliable, and stall-free.