4F27E Transmission Solenoid Block Module, 48420K-R

A Focus or a Mazda with the four-speed automatic that refuses to upshift past second, bangs into gear, or drops into limp mode with two or three shift solenoid codes at once is a classic candidate for this part. This is the complete solenoid block for the Ford 4F27E, the transaxle Mazda calls the FN4A-EL, sold under interchange number 48420K-R. Instead of buying solenoids one at a time and hoping you found the bad one, you replace the whole assembly that bolts to the lower half of the valve body in one job.

What the solenoid block does in a 4F27E

The 4F27E has no throttle cable or governor. Every shift is decided by the powertrain computer, and the solenoid block is how that decision becomes oil pressure. TransGo's valve body layout for this unit shows the block carrying the pressure control solenoid along with shift solenoids A through E. The shift solenoids send signal oil to the shift and clutch control valves, one of them handles the converter clutch, and the pressure control solenoid sets line pressure against throttle opening and load. Because all of these sit on one cast body with their own connectors, the block comes out and goes in as a unit, which is why rebuilders often change the whole block once more than one circuit is acting up.

One detail trips people up when reading codes or service info: Ford and Mazda label the same solenoids with different letters. A Mazda manual and a Ford scan tool can name two different parts for the same fault, so go by position on the block, not by the letter alone.

Symptoms that point to the solenoid block

• Stuck in second or third with the wrench light or check engine light on
• Harsh engagement into Drive or Reverse, or a hard 1-2 shift
• Erratic shift timing that changes as the fluid warms up
• Several shift solenoid circuit or performance codes stored together
• Wrong-gear starts or a missing second gear, which on this family can also come from valve body bore wear and separator plate cross-leaks with codes P0731, P0732, P0741 or P0757

How to confirm it before you buy

Check fluid level and condition first; low or burnt fluid gives the same complaints and new solenoids will not fix worn frictions. Then pull every stored code and road test, noting which gear or shift misbehaves. Measure each solenoid at the case connector for open or shorted circuits and inspect the harness and pins for oil intrusion or chafing. Converter slip codes deserve extra care: Transmission Digest traces P0741 on the 4F27E and FNR5 to worn converter clutch valve bores and pump bushing leakage, which no solenoid replacement cures. If the solenoids test good and the bores are the problem, a complete 4F27E valve body with solenoid harness is the better buy.

Fitment

The listing covers 2000-2012 Ford Focus and 2011-2012 Ford Fiesta four-speed automatics, and it cross-references the Mazda-badged members of the family. Be careful at the ends of that range: in the North American market the 2012 Focus and the 2011-2012 Fiesta automatics are the six-speed dual-clutch, which shares nothing with this block, so confirm the tag on your case reads 4F27E or FN4A-EL. The block also changed during production, so match the connector shapes and bolt pattern on your old block against the photos, or send us your year and VIN before ordering. Everything else we carry for this transaxle is on the 4F27E parts page.

Install notes

• The block mounts on the valve body; drain the fluid and follow the service manual for your car to reach it, keeping the vehicle level.
• Unplug each connector by hand and note its position before removing the block bolts.
• Clean the mating surface, check that the separator plate and gaskets are seated, and torque the block bolts evenly in steps so the body does not distort.
• Change the filter and pan gasket while the fluid is out; our FN4A-EL filter and pan gasket kit fits Mazda 3, 5 and 6 units.
• Refill with Mercon V on Ford-built units; Mazda-badged units call for Mazda's own ATF, and our Idemitsu ATF Type M case is listed for those applications.
• Clear codes and drive through every gear several times so the adaptive shift strategy can relearn.

If you only need individual solenoids and a filter rather than the whole block, compare the 4F27E shift solenoid and filter kit.

Does this block fit my 2012 Ford Focus?

Only if your car has the four-speed 4F27E. Most 2012 North American Focus automatics are the six-speed dual-clutch, which uses completely different parts. Check the transmission tag or send us your VIN.

Why replace the whole block instead of one solenoid?

When several solenoid codes set together, or the car has been in limp mode more than once, chasing one solenoid at a time usually costs more in labor and fluid than changing the full block. A single code with all other circuits testing good can be handled with individual solenoids.

My scan tool says solenoid B but the Mazda manual shows a different part. Which is right?

Both can be. Ford and Mazda letter the solenoids differently on this transaxle, so identify the solenoid by its location on the block rather than by the letter alone.

Will a new solenoid block fix P0741?

Not always. On the 4F27E and FNR5, P0741 is often caused by wear in the converter clutch valve bores or pump bushing leakage, not by the solenoid. Test the solenoid circuits first; if they are good, look at the valve body.

What fluid do I use after installing it?

Ford-built 4F27E units use Mercon V. Mazda FN4A-EL units call for Mazda's specified ATF. Refill to the correct level using the check procedure for your vehicle.

Do I need a relearn after install?

Clear the codes and drive the car through full shift cycles. The computer adapts shift pressure over the first several drives, so expect shift feel to settle in after a few days.