P0747 on GM 10L80 and 10L90: Feed Limit Valve Wear and the Fix

P0747 on GM 10L80 and 10L90: Feed Limit Valve Wear and the Fix

If you own a late-model GM truck or SUV with the 10-speed automatic and the check engine light just came on with P0747, you are not dealing with a random electrical gremlin. You are looking at the same worn valve that put tens of thousands of GM vehicles under a federal safety recall. The good news is that it is a known, documented failure with a known fix. The bad news is that the recall software does not repair the mechanical problem, and driving on it will cost you clutch packs.

What P0747 means on a GM 10-speed

P0747 sets as Transmission Control Solenoid Valve 1 Stuck On, and it drops the transmission into a limp mode limited to 5th gear and reverse, per GM service bulletin 25-NA-255 (issued September 22, 2025). Owners describe it as the truck suddenly refusing to shift, a hard clunk, or the dash lighting up on the highway with no warning.

Common complaints that show up alongside the code:

  • Harsh or delayed engagement, especially once the transmission is hot
  • A sudden drop from 7th or 8th gear down to 2nd at speed
  • Momentary rear wheel lock-up during a downshift at highway speed
  • Limp mode that clears on a restart, then comes back after the fluid heats up

That last one is the single most useful diagnostic clue, and we will come back to it.

The recall: what GM covered and what it did not

In March 2025, GM issued Safety Recall N242480630 covering the 10L1000 and Gen. 2 10L60, 10L80 and 10L90 transmissions, per a Sonnax tech bulletin by Jim Dial. The recall language describes a momentary wheel lock-up condition at higher speeds that can also include a downshift back to 2nd gear.

That campaign has kept growing. In February 2026, GM recalled another 44,787 trucks and SUVs for the same defect, according to Carscoops: 43,732 2022 Tahoe, Suburban, Yukon, Yukon XL, Escalade and Escalade ESV models, plus 1,055 2020-2022 Silverado 1500 and Sierra 1500 units and some 2500/3500 trucks. Valero Law notes the expansion leaned toward vehicles with Electronic Transmission Range Select (ETRS).

Here is the part owners miss. The recall remedy is a transmission control module software update, not a mechanical repair. The calibration watches for the pressure signature of a worn valve and, per Carscoops, flags it roughly 10,000 miles before it could cause a lock-up, then limits the transmission to 5th gear and turns on the service light. Sonnax makes the same point: the software prevents the road hazard, but the wear is still sitting in your valve body. A recall-complete vehicle can still fail. The software just makes the failure boring instead of dangerous.

Root cause: the feed limit low valve

Per the Sonnax bulletin, the loss of control pressure traces to the feed limit low valve. That valve lives in the boost ball circuitry, and it has a second job: it acts as a solenoid regulator limiting solenoid feed to the default disable (DD) on-off solenoid.

The DD solenoid controls two valves in the upper valve body, the default enable valve and the default select valve. Those two run the power-down default drive mode, which is 2nd gear in Drive and reverse. The DD solenoid is powered on at all times and only turns off when a default event occurs, at which point pump pressure gets routed through the default valves into the exhaust passages to apply clutches.

Now put the wear in: as the feed limit low valve bore wears, solenoid feed pressure to the DD solenoid drops, and the default valves can move when they should not. Sonnax notes that depending on which solenoids are applied and what gear is commanded, this can drop the transmission into lower gears or create a bind-up. A bind-up at highway speed with the rear wheels driving is exactly the wheel lock-up the recall describes.

Mileage is not much protection. Sonnax reports 10L1000 units wearing this valve out in as few as 35,000 miles, with tow trucks and trailer haulers hit hardest. Heat and sustained load are what kill it.

How to confirm it before you spend money

  1. Note whether it is temperature dependent. Per Sonnax, the transmission will usually behave normally until it is hot. If the truck drives fine cold and acts up after 20 minutes, that points hard at valve bore wear rather than a solenoid or a wiring fault.
  2. Pull codes and freeze frame. P0747 with a hot-fluid freeze frame is the signature. Sonnax describes P0747 on this unit as the "E" clutch being on when it should be off.
  3. Drop the pan and read the debris. This matters for repair strategy, not just diagnosis. GM's bulletin instructs technicians not to perform the in-valve-body repair if excessive clutch debris is present in the pan. Debris means the clutches are already gone and you are into a rebuild.
  4. Vacuum test the valve. Sonnax specifies testing the balance end of the feed limit low valve, which is where it wears most, and comparing the result to the feed limit high valve. Those are the same valve trains with different springs. A typical good reading is 18 inches of mercury or higher. Below 8 inches of mercury, Sonnax says the bore is worn far enough that a drop-in valve will not make up for it and you should be reconditioning the bore with an oversized kit.

Do not keep driving it. Sonnax warns that extended driving in this condition will destroy the clutch packs, because the unit will intermittently bind up. A valve repair is cheap. A rebuild after the clutches cook is not.

The fix

Until late 2025, the dealer answer was to replace the whole control valve body assembly, often with a solenoid body and recalibration on top of it. GM changed that with TSB 25-NA-255, which replaces the swap with a bench repair of the valve body you already have.

Per the bulletin, the repair installs three updated pieces:

  • An upgraded steel feed limit low valve (part 24059372)
  • A higher tension feed limit valve spring (part 24279142)
  • A new valve body spacer plate with gasket (24075088 on MQB diesel, 24075090 on MQC diesel)

The bulletin applies to 2021-2024 Silverado and Sierra 1500 with the LM2/LZ0 diesel and select 2021-2024 Escalade, Tahoe, Suburban and Yukon models, across the MQB, MQC, MHS, MHT, MHU, MI2 and MHO transmission RPOs. Two service notes worth knowing: the vehicle must have at least 7,000 miles for the repair to apply, and no solenoid recalibration is required afterward. Most valve body fasteners torque to 80 in-lb (9 N-m).

Remanufactured automatic transmission valve body, Sonnax updated and dyno tested
Shop remanufactured transmission valve bodies →

The aftermarket path is a drop-in valve kit. Sonnax offers feed limit low valve kit 105740-54K and feed limit high valve kit 105740-58K for the 10L1000 and Gen. 2 10L60/80/90, plus oversized kits 105740-59K and 105740-60K when the bore is too far gone for a drop-in. We stock the Sonnax 10L80 valve body kit for that repair, and a complete ACDelco 10L80 valve body for units where the bore is beyond reconditioning or the pan came apart full of debris.

Replace while you are in there

The pan is already down and the fluid is already out. Do not put it back together twice:

  • Filter and pan gasket. The WIX 10L80 filter is a few dollars against several hours of labor.
  • Spacer plate and gasket. GM includes it in the repair for a reason. Do not reuse a plate you just unbolted.
  • Feed limit high valve. If the low valve wore, vacuum test the high valve while the body is on the bench. Same train, same wear mechanism.
  • Fresh fluid to spec. Refill with the fluid GM specifies for your RPO. This is not the place to experiment.

Cost and effort

This is a pan-down, valve-body-out job under the vehicle, then a bench repair. Intermediate difficulty: no transmission removal, no case splitting, but you are handling small valves and springs that must go back in clean and in order, and every fastener has a torque spec. A DIYer with good stands, a torque wrench that reads in inch-pounds, and patience can do it in a weekend. Most shops treat it as a several-hour in-vehicle repair.

Ignore it and bind-up events chew the clutch packs, turning a valve and a spring into a full rebuild. Fix the valve while the clutches are still alive.

FAQ

My truck already had the recall software done. Am I safe?
You are safer, not fixed. The calibration detects the worn valve and limits the transmission to 5th gear so the wheels do not lock up, per Carscoops. The worn valve is still in the valve body. Expect it to eventually put you in limp mode.

Why does it only act up when the transmission is hot?
Hot fluid is thinner and leaks past a worn bore more easily, so control pressure falls off. Sonnax specifically calls out letting the vehicle cool as a quick check, because the unit usually functions normally until it heats up.

Can I just replace a solenoid instead?
No. P0747 names a solenoid valve, but on this unit the documented root cause is bore wear at the feed limit low valve, not a failed solenoid. Vacuum test before you buy parts. If the balance end reads below 8 inches of mercury, the bore itself needs reconditioning.

For a closer look at how to separate valve body problems from converter problems on this platform, read our guide on diagnosing 10L80 shudder at 40 mph.

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