4T40E Solenoid Kit 2007-2009

Late-model GM four-speed cars are the ones this kit is aimed at: a 2007-2009 Chevrolet Cobalt, HHR or Malibu, Pontiac G5 or G6, or Saturn Aura that locks itself in second gear, slams the 1-2 shift, or flares into third once the fluid is hot. On those cars the electrical parts bolted to the 4T40E or 4T45E valve body wear out long before the hard parts do. The kit pictured replaces the full electronic set in one pan-off job: shift solenoids A and B, the torque converter clutch solenoid, the electronic pressure control solenoid and the pressure switch manifold.

What the solenoid kit does in a 4T40E

Nothing in a 4T40E shifts on its own. The engine computer reads speed, throttle and load, then switches shift solenoids A and B on and off in combinations that select first through fourth. The EPC solenoid is a variable force motor that sets line pressure, which decides how hard each clutch and band is squeezed during and after the shift. The converter clutch solenoid locks the converter at cruise and releases it for coast-down and stops. The pressure switch manifold reports manual valve position back to the computer so it knows whether the selector is in Park, Drive or a manual range. If any one of those parts reports wrong or reacts slowly, the computer and the hydraulics stop agreeing, and the result is limp mode, a harsh shift or a slip.

Symptoms of worn 4T40E solenoids

• Car starts in second or holds second gear with the check engine light on
• Hard 1-2 or 2-3 upshifts, or a bang when coming to a stop
• Slipping or flared shifts once hot, often from a tired EPC solenoid
• Shudder at 40-50 mph cruise, or stalling at a stop because lockup does not release
• Shift solenoid codes P0751, P0752, P0753 or P0758, or range switch codes from the manifold

How to confirm it before you buy

Pull the dipstick before anything else. Black, burnt-smelling fluid means the 2nd or 4th clutch is already damaged, and solenoids will only mask it. Next read every stored code and check each solenoid circuit with a meter at the case connector, then again at the solenoid, so a broken wire or cracked internal harness does not get blamed on a good part. Converter codes P0741 or P0742 can be a hydraulic problem: TransGo documents pressure regulator bore wear on 4T40E and 4T45E units from 1995 on as a cause of those codes and burned frictions. When the bores are worn, the right part is a 2007 4T40E valve body rather than solenoids alone, and a 2007-2009 shift kit addresses the pressure regulation side during a rebuild.

Fitment

This listing is for 2007-2009 4T40E applications, which in that window covers the Chevrolet Cobalt, HHR and four-cylinder Malibu, the Pontiac G5, and the 4T45E-equipped G6 and Saturn Aura. The 4T40E (RPO MN4) and 4T45E (RPO MN5) share this electronic layout, so check the RPO code on the service parts label before ordering. The EPC solenoid is the part to watch: Sonnax documents that valve bodies through 2003 use a large Delphi EPC, while 2004 and later bodies use a small Bosch style that fits the same bore. A 2007-2009 car must get the later small style; mixing them causes soft or harsh shifts without always setting a code. Compare connectors and the EPC body against your old parts, or send your year and VIN. Earlier and broader kits, plus everything else for this unit, are on the 4T40E parts page.

Install notes

• Drain the fluid first, then follow the service manual for your car to reach the valve body that carries these solenoids, keeping track of every bolt length as it comes out.
• Replace one solenoid at a time so each lands in its original bore and bracket.
• Use new O-rings on every solenoid, lubricated with clean fluid, and torque the manifold and bracket bolts evenly.
• Install a new 4T40E/4T45E filter and pan gasket kit while you are in there.
• Refill with Dexron VI ATF, check the level hot, clear codes and let the computer relearn shift pressures over several drives.

Does this kit fit a 2007 Pontiac G6 with the 4T45E?

The 4T40E and 4T45E use the same solenoid and pressure switch layout, so the kit is built for both. Confirm your RPO code (MN4 or MN5) on the service parts label and compare the connectors before installing.

Why does the EPC solenoid style matter for 2007-2009?

GM switched from a large Delphi EPC to a small Bosch EPC in 2004. Both fit the same bore, but the wrong one in a 2007-2009 valve body causes soft or harsh shifts. Your car needs the later small style.

My Cobalt is stuck in second. Will this fix it?

Second-gear limp mode is the computer's failsafe. If the codes point to shift solenoid A or B, the pressure switch manifold, or their circuits, and the fluid is healthy, this kit is the usual fix. Check wiring first, because a broken harness wire sets the same codes.

What fluid does the 4T40E use?

Dexron VI ATF. Check the level with the engine running and the fluid at operating temperature.

How do I know which solenoid goes where?

Swap them one at a time, matching each new part to the old one by shape, connector and bracket. Shift solenoids A and B look alike, so keep their positions straight. Use the service manual for your vehicle for torque values.

Should I replace anything else at the same time?

Change the filter and pan gasket while the fluid is out. If you have converter slip codes with good solenoids, inspect the valve body for pressure regulator bore wear.