Harsh shifts, banging when shifting gears.
Older Peugeots that use a ZF 4HP20 4-speed transverse automatic transmission, designated as A4L, can suffer from harsh gear changes coupled that are followed by loud bangs.
This will usually trigger a 'check gearbox' warning message on the central display. In most cases, the problem will be intermittent and happen after the vehicle warms up.
- The faulty pressure regulator is responsible for maintaining an adequate pressure of transmission fluid. The source of the problem is a spring inside the regulator, which wears out and causes pressure loss. This results in harsh gear shifts. Replacing the regulator is the only solution.
- Sticking or clogged Lock-up solenoids, causing delays in gear shifts. This, in the end, results in harsh gear engagement because of the differences in rotational speeds.
Slippage or loss of 3th and 4th gear
Peugeots with smaller engines with a 6-speed automatic gearbox designated as TF70 can develop a noticeable slippage when engaging 3rd or 4th gear.
This will start as an intermittent problem that only occurs while driving for a longer period but can worsen with time. In some cases, it can even lead to the loss of affected gears.
- Worn K-2 clutch, causing a cross leak inside the valve sleeve. The resulting oscillation in hydraulic pressure prevents proper clutch actuation, which affects gear shift quality. Reconditioning the bore and installing an oversized K2 clutch control valve kit will solve the problem.
Transmission Stuck in Limp mode.
Older Peugeots that use a ZF 4HP20 4-speed transverse automatic transmission, designated as A4L, can have intermittent problems with going into limp mode. The usual scenario is that the car starts and drives fine for a couple of miles before suddenly going into limp mode.
When this happens, the transmission will stay stuck in 3rd gear, and there will be a 'Gearbox faulty' warning on the central display.
- Low transmission fluid level, which will trigger a P1167 error code. The transmission switches to limp mode to prevent the damage caused by overheating and lack of lubrication.
- Faulty pressure modulation valve, causing increased differences in transmission fluid pressure during gear changes. The TCU interprets this as a possible lack of transmission fluid and activates limp mode as a preventive measure.
Shift flares and delayed downshifts.
Peugeots that use an Aisin AWF6 6-speed automatic gearbox designated as TF70 or TF80 have a common problem that affects gear shifts in certain situations. This can show up either as shift flares on accelerations or delays in downshifts when coming to a stop.
In the initial stages, these symptoms will be sporadic and only happen during slow accelerations but will worsen with time.
- Excessive transmission fluid deterioration or dirty filter as a result of not changing the fluid. This is very common on high-mileage cars, as the manufacturer claims this is a 'sealed for life' transmission. Check the service history, and flush the transmission fluid if needed. Be careful to use the approved transmission fluid.
- Excessive bore wear inside the valve body causes losses of transmission fluid pressure and results in various shift issues. Replacing the whole valve body is the only solution, but many specialized workshops sell rebuilt ones because this is a well-known problem.
Harsh shifting into reverse or 3rd and 4th gear
Peugeots that use an Aisin AWF6 6-speed automatic gearbox designated as TF70 or TF80 can suffer from harsh or delayed gearshifts. This is an issue that will happen while the engaging reverse, 3rd, or 4th gear. Other gears will not be affected.
In most cases, the problem will be sporadic and more prominent when the vehicle reaches running temperatures.
- Damaged balance piston for K-3 clutch, which acts as a return and accumulator that counteracts the K-3 application. This causes sharp engagement of the K-3 clutch, which operates affected gears. There are aftermarket pistons that will eliminate the radial piston movement and solve the issue.
These are some of the most common problems that affect Peugeot automatic transmissions. It doesn't mean that every Peugeot vehicle will have transmission problems.