P0776 on 2007-2009 Saturn Aura: Pressure Control Solenoid 'B' and Wave Plate Failure Guide

What's Unique About the 2007-2009 Saturn Aura

For the 2007-2009 Saturn Aura equipped with the 6-speed automatic transmission (GM 6T70), this code is notoriously symptomatic of a much larger problem. These transmissions have a well-documented design flaw where the 3-5-R clutch wave plate fractures. GM Technical Service Bulletin 🎬 Watch: See how a broken wave plate causes these codes 09-07-30-012F explicitly states that P0776 is a primary code set by this failure. Manufacturer TSB Bulletin #PI0780A also provides repair information for cases where the MIL is illuminated and DTC P0776 is set alongside concerns of slipping, no reverse, or no 3rd gear. When the plate breaks, metal fragments are sent throughout the transmission. This debris clogs the control solenoid filter plate and can cause the solenoids themselves to stick, leading to the P0776 code. The failure ultimately results in a loss of hydraulic pressure for the 3-5-R clutch pack, causing the loss of 3rd, 5th, and Reverse gears.

Symptoms You May Notice

• Complete loss of 3rd, 5th, and Reverse gears.
• Harsh, jerky, or flaring shifts, especially between 2-3 and 4-5.
• Transmission slipping or failing to engage properly from a stop.
• Illuminated Check Engine Light with code P0776 stored.
• Transmission may enter 'limp mode', often stuck in 2nd or 4th gear.
• Delayed engagement when shifting into Reverse.

Most Likely Causes

1. Broken 3-5-R Wave Plate 🔴 High Probability This is a well-documented design flaw in the first-generation GM 6T70/6T75 transmission. The original wave plate was not properly stress-relieved and was prone to fracturing. GM issued multiple 🎬 Watch: Expert breakdown of common 6T70 design issues TSBs (e.g., 09-07-30-012F, 14404A) and a special coverage program to address this widespread failure.
   How to confirm: Definitive confirmation requires a transmission teardown. However, the combination of code P0776 and the loss of 3rd, 5th, and Reverse gears is a near-certain diagnosis. NHTSA ODI #10723108 notes that the 6-speed automatic transmission may experience no reverse and slip/flare/harsh shifts in 3rd and/or 5th gear specifically when P0776 and P0842 are present. An owner on an Edmunds forum described these exact symptoms, which required a full transmission replacement due to the broken wave plate.
   Typical fix: The transmission must be removed, disassembled, and rebuilt with an updated, more robust wave plate (ACDelco P/N 24254103). TSBs mandate that the entire transmission be disassembled to clean out all metal debris and that the pump fluid filter and control solenoid filter plate must be replaced to prevent a repeat failure.
   Est. part cost: $300-$600 for a full rebuild kit including an updated wave plate and new seals.
2. Failed Pressure Control Solenoid 'B' (or TEHCM) 🟡 Medium Probability → Shop Transmission Valve Body The solenoid itself can fail, but it is most often a secondary failure. Metal debris from the broken wave plate clogs the valve body and solenoid screens, causing the solenoid to stick or burn out. Replacing only the solenoid without addressing the debris will result in a quick repeat failure.
   How to confirm: A technician can command the solenoid with a high-end scan tool to check its response. However, even if the solenoid fails this test, it is likely a symptom of the wave plate failure. Dropping the pan and finding glitter-like metal debris is the key indicator.
   Typical fix: Replacement of the entire TEHCM (solenoid pack). This should ONLY be done after the transmission has been fully inspected and cleaned of all wave plate debris. The TEHCM must be programmed after installation.
   Est. part cost: $200-$500 for a TEHCM unit.
3. Low or Contaminated Transmission Fluid ⚪ Low Probability → Shop Transmission Assembly This is almost always a symptom, not a cause. The fluid becomes contaminated with metallic particles from the disintegrating wave plate. Low fluid from a leak can cause pressure issues, but is unlikely to be the root cause of P0776 in this specific vehicle.
   How to confirm: Check the transmission fluid level and condition. If the fluid is dark, has a burnt smell, or contains visible metallic particles ('glitter'), it confirms severe internal damage, almost certainly from the wave plate.
   Typical fix: If the fluid is contaminated, the transmission requires a full rebuild. Simply flushing the fluid will not remove all the debris or fix the broken plate.
   Est. part cost: $50-$150 for fluid and filter, but this will not solve the problem.

Rare But Worth Checking

• Faulty Transmission Control Module (TCM): → Shop Transmission Assembly The TCM is integrated into the solenoid pack (TEHCM) on the 6T70 transmission. While the TEHCM can fail, it's far less common than the mechanical wave plate failure. TSB 09-07-30-012F specifically warns against replacing the TEHCM for this code unless all diagnostics have been completed and point to it as the primary failure.
• Damaged Wiring Harness: An internal or external wiring issue could prevent the TCM's signal from reaching the solenoid. This is possible but extremely unlikely compared to the known mechanical flaws of this transmission. A technician on a forum noted that a high-resistance short in a ground wire caused significant voltage drops and electrical issues on a 2008 Aura.

Diagnosis Steps

1. Check the transmission fluid level and condition. Look for a dark, burnt smell or visible metal particles ('glitter') on the dipstick.
2. Scan the TCM for all stored trouble codes. Note if other solenoid codes (P0777, P0796, P2714) are present, as this strongly suggests widespread contamination. NHTSA ODI #10597630 describes an owner receiving codes P0700 and P0776 from the engine, which ultimately pointed to a broken wave plate.
3. Given the extremely high probability of wave plate failure on this platform, the most effective diagnostic step is to drop the transmission pan.
4. Inspect the pan magnet and fluid for excessive metallic debris. A silver, glitter-like sludge is the classic sign of wave plate failure.
5. If significant debris is found, the transmission must be removed and disassembled for a full rebuild. No further electronic diagnosis is necessary as the root cause is mechanical.
6. If, in the rare event no debris is found, proceed with electronic testing of the solenoid circuits and TEHCM as per the service manual.

Parts You'll Likely Need

• Transmission Rebuild Kit (with updated wave plates) — This is required to fix the root cause. A full kit ensures all clutches, seals, and gaskets are replaced along with the faulty wave plate.
  Trusted brands: ACDelco, Transtar, Alto
  OEM price range: $400-$600
  Aftermarket price range: $250-$450
• 3-5-Reverse Clutch Wave Plate (Updated Design) (OEM #24254103) — This is the specific part that fails. The updated ACDelco part is stress-relieved to prevent a repeat failure. It must be installed during a rebuild.
  Trusted brands: ACDelco (OEM)
  OEM price range: $15-$30
  Aftermarket price range: $10-$20
• Transmission Electro-Hydraulic Control Module (TEHCM) — This unit contains all the solenoids and the TCM. It often gets damaged by debris and may need replacement during a rebuild, but it is not the root cause. It requires programming upon replacement.
  Trusted brands: ACDelco (OEM), Dorman (Remanufactured)
  OEM price range: $300-$500
  Aftermarket price range: $200-$400

Related Codes That Often Appear With This One

• P0796 — Pressure Control Solenoid 'C' Performance or Stuck Off. Debris affects multiple solenoids.
• P0777 — Pressure Control Solenoid 'B' Stuck On. The opposite state, but caused by the same debris contamination.
• P2714 — Pressure Control Solenoid 'D' Performance/Stuck Off. TSB 09-07-30-012F lists this as another potential code caused by wave plate debris.
• P0842 — Transmission Fluid Pressure (TFP) Switch 1 Circuit Low Voltage. Also cited in TSBs as a related code.

Technical Service Bulletins (TSBs) & Recalls

• TSB 14404A / 14404B: 'Special Coverage Adjustment – Transmission Clutch Wave Plate'. This bulletin acknowledges the fractured wave plate, lists the affected vehicles including the Saturn Aura, and details the extended warranty coverage GM provided (10 years/120,000 miles) for the repair.
• TSB 09-07-30-012F: 'No Reverse, 3rd or 5th, Check Engine Light Illuminated, DTC P0776'. This is a key technical document that directly links code P0776 to the broken 3-5-R wave plate. It instructs technicians to replace the wave plate and thoroughly clean the transmission of all debris.
• TSB Bulletin #PI0780A: This informational bulletin provides repair information to correct customer concerns of slipping, no reverse, no 3rd gear, or no forward movement when DTC P0776 is set.

Platform-Specific Known Issues

• The 6-speed automatic transmission (6T70) used in the 2007-2009 Saturn Aura is infamous for a fractured 3-5-R wave plate. GM issued Technical Service Bulletin 09-07-30-012F and Special Coverage 14404A to address this. The failure causes a loss of 3rd, 5th, and Reverse gears and triggers solenoid codes like P0776 as a secondary symptom due to metal debris contaminating the valve body.

Mechanic-Grade Diagnostic Values

• Shift Solenoid Resistance — expected: 20-40 ohms. Failure: A reading outside this range indicates a faulty solenoid coil.
• PWM VBS (Variable Bleed Solenoid) Resistance — expected: 4-7 ohms. Failure: A reading outside this range indicates a faulty solenoid coil. These values will vary with temperature.
• Ground Circuit Voltage Drop — expected: Under 100 millivolts (0.1V). Failure: A reading of 220mV from the engine block to battery negative indicates high resistance in the ground circuit. One technician found a voltage drop of over 5 volts on the ground side under a 2-amp load, indicating a bad ground connection at G107.

Scan Tool Commands That Help

• GM Tech2 / GDS2 or equivalent professional scan tool: Service Fast Learn Adapts — This procedure is required after replacing the transmission, TEHCM, or performing any internal repairs. It allows the TCM to relearn clutch apply pressures and shift timing. Failure to perform the fast learn can result in poor shift quality.
• GM Tech2 / GDS2 or equivalent professional scan tool: Solenoid Activation Test — To individually command each solenoid on and off to check for mechanical response. This is typically done with a special test plate and regulated air pressure on the bench to see if the solenoid is physically sticking. However, for P0776 on this vehicle, this is often a secondary test as the root cause is mechanical (wave plate).
• GM Tech2 / GDS2 or equivalent professional scan tool: Reset Transmission Adapts — This function erases all learned transmission adaptive pressure (TAP) values. It should be performed after component replacement or reprogramming to allow the TCM to start a fresh learning process.

Wiring & Ground Locations

• G107 — On the right front of the engine.. This is a shared ground point for multiple components, including the Transmission Control Module (TCM). A poor connection here can cause high resistance, leading to significant voltage drops and erratic behavior of the transmission electronics, potentially mimicking solenoid or module failure.
• TEHCM Main Connector — External 20-pin connector on the transmission side cover, which passes through to the internal TEHCM.. This is the primary electrical interface for the entire valve body, including all solenoids and the integrated TCM. All power, ground, and communication signals pass through here. Damage to this connector or its seal can cause fluid leaks or electrical faults.
• Harness Chafe Point — A potential chafe point was identified where the engine wiring harness can rub against the cylinder head.. While not directly linked to P0776 in the source, a damaged harness in this area could short a circuit related to the transmission, causing intermittent electrical faults. A visual inspection of harness routing is a wise step during diagnosis for any electrical code.

Real Owner Repair Stories

• Edmunds Car Forums (2007 Saturn Aura, 50,000 miles) — Unspecified transmission failure.
  ✅ What actually fixed it The user reported the waveplate broke and required a complete transmission replacement at a cost of $3,800.
• Saturn Forum (2008 Saturn Aura) — Multiple electrical issues, including low voltage to control modules.
  ❌ Tried (didn't work) Initial checks of power circuits.
  ✅ What actually fixed it The problem was a high-resistance short in the ground circuit. A load test on the ground side showed a voltage drop of over 5 volts. Cleaning the common ground point (G107) resolved the issue.
• NHTSA ODI #10597630 — An owner reported that their wave plate broke, an issue they noted has been happening to Saturn cars for years, resulting in error codes P0700 and P0776.

OEM Part Supersession History

• Unknown (Original factory-installed wave plate) → ACDelco 24254103 — The original wave plate was not properly stress-relieved and was prone to fracturing at the splines. The updated OE part is heat-treated and stress-relieved to prevent this failure.
• ACDelco 24254103 (Waved plate with internal teeth) → Sonnax 124555K (Drum Saver Kit) — The Sonnax kit includes a redesigned wave plate that has no internal teeth, eliminating the stress points where cracks typically form. It is paired with a custom cupped steel plate to maintain proper clutch pack operation. This design is considered more robust than even the updated OE part.
  Heads up: This is a kit, not a direct plate replacement. It includes a specific cupped steel that must be used with the toothless wave plate.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Stretched Timing Chains (3.6L V6 LY7 Engine) 🔴 High — Very common, often appearing between 70,000 and 120,000 miles. Triggers codes like P0008, P0017, P0016. (Ref: Special Coverage Adjustment #11340 (now expired) was issued for other GM models with this engine.)
• Power Steering Failure (Hydraulic on V6, Electric on I4) 🟠 Medium — V6 models experience whining pumps and fluid leaks, while 4-cylinder models suffer from sudden loss of electric power assist. (Ref: NHTSA Campaign 14V153000 was a recall for the Electric Power Steering (EPS) on 4-cylinder models, not the V6 hydraulic system.)
• Blown High-Speed Cooling Fan Fuse 🟠 Medium — The 30-amp fuse for the cooling fan can blow, leading to engine overheating, especially in traffic.
• EVAP System Faults (Vent Valve/Solenoid) 🟡 Low — A failing EVAP vent valve or solenoid is common, causing a Check Engine Light (often for a small leak) and difficulty filling the gas tank.
• Shift Cable Failure (4-Speed Automatic Only) 🔴 High — Affects models with the 4-speed automatic, not the 6-speed associated with P0776. The shift cable end tabs can fracture, preventing gear selection. (Ref: NHTSA Recall 12V460000.)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this specific P0776 failure, sourcing a complete used transmission is extremely risky and generally not recommended. The wave plate failure was a design defect, so a used unit from a 2007-2009 donor vehicle likely has the same faulty part and may be close to failure itself. A used TEHCM is also a poor choice, as it may have been contaminated by debris from the donor vehicle's failing transmission.

What to inspect on the donor part:

• If forced to consider a used transmission, it MUST come with verifiable documentation that it has already been rebuilt with the updated 3-5-R wave plate.
• Ask for receipts or a report from the rebuilder.
• Avoid any transmission from this era sold 'as-is' without a rebuild history.

OEM-only on this vehicle (don't cheap out):

• Transmission Rebuild Kit: While aftermarket kits exist, using a kit with an ACDelco updated wave plate (P/N 24254103) is a proven, safe bet.
• Transmission Fluid: Use only DEXRON-VI fluid as specified by GM. Using incorrect fluid can cause shift problems and damage.

Aftermarket brands forum-validated for this vehicle:

• Sonnax: Their 3-5-R Drum Saver Kit (124555K) is a highly regarded aftermarket solution that improves upon the OEM design by removing the failure-prone teeth from the wave plate.

Brands owners have reported issues with on this vehicle:

• There are no specific brands frequently cited for avoidance, but caution should be exercised with unbranded, 'white-box' rebuild kits or individual wave plates from unknown sources, as their material quality and manufacturing process may not meet the required standards to prevent a repeat failure.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0777 — This is the 'stuck on' companion code for Pressure Control Solenoid 'B'. It often appears with P0776 when metal debris from the failed wave plate causes widespread contamination and erratic solenoid operation.
• P0796 — This code for Pressure Control Solenoid 'C' often appears alongside P0776. Its presence strongly suggests that metal debris from the broken 3-5-R wave plate has contaminated the entire valve body, affecting multiple solenoids.
• P2714 — This code for Pressure Control Solenoid 'D' can be triggered as a secondary fault when metallic particles from the fractured wave plate clog the TEHCM and valve body, causing widespread hydraulic control issues.
• P0842 — This code for the Transmission Fluid Pressure Sensor is often set concurrently with P0776 when the 3-5-R wave plate breaks, as the significant internal mechanical failure causes erratic hydraulic pressure readings within the transmission.

Frequently Asked Questions