ZF8HP Jeep Grand Cherokee Common Problems and Fixes

From the 2014 model year on, the WK2 Grand Cherokee dropped the old five-speed for an eight-speed built on the ZF 8HP design, and the 2021-up WL kept an eight-speed of the same family. Across the V6, Hemi, EcoDiesel and SRT versions, the complaints that come through the door are mostly calibration, false codes, fluid level and age, and valve body wear. The shifter recall comes up too. Very few of these Jeeps need the transmission out to fix the first complaint.

Below is what each problem looks like, what FCA, ZF and Sonnax actually published about it, and the order I work them in on a Grand Cherokee.

Recommended ZF 8HP parts for the Grand Cherokee

A pan, filter and ATF kit for the overdue fluid service, a 9-piece solenoid kit for the 845RE and 8HP70 mechatronic, and a remanufactured 8HP70 valve body with solenoids for Hemi, diesel and SRT Jeeps with worn bores. Match the part to your sales code. Secure checkout on our own site.

ZF 8HP70 Transmission Pan, Filter & ATF Kit RAM/Jeep/Dodge

$254.99View part

ZF 8HP45/8HP70 Mechatronic Solenoid Kit, 9-Piece

$175.99View part

8HP70 Valve Body with Solenoids, Remanufactured

$393.99View part

First: Which Eight-Speed Is in This Grand Cherokee?

This Jeep had more engine options than most vehicles that got the ZF-based unit, and the transmission changes with the engine. FCA's own bulletins tell you which pairing you have by sales code. Bulletin 21-039-14 lists the 2015 WK with the 3.6L Pentastar (engine code ERB) on the 845RE (transmission code DFL), and the 5.7L Hemi (EZH) on the 8HP70 (DFD or DFK). Bulletin 21-045-15 puts the 3.0L EcoDiesel (EXF) on the 8HP70, and bulletin 21-018-15 puts the 6.4L SRT (ESG) on the 8HP70 as well. For the 2021 WL, bulletin 21-027-21 pairs the 3.6L (ERC) with the 850RE (DFT), the second-generation light-duty unit.

The 845RE is Chrysler's build of the lighter ZF 8HP45 design. A V6 Jeep and a Hemi Jeep do not share a valve body or hard parts, and a WK2 part will not fit a WL. Read the sales code off the build sheet or the tag on the case before you order anything.

Problem 1: Shift Complaints That Are Really Calibration

The early WK2 eight-speeds got a long run of TCM reflashes, and almost every one of them lists a complaint an owner would call a bad transmission. If the Jeep has never had its TCM updated, that is the first thing to check.

• 3.6L / 845RE. Bulletin 21-039-14 (November 2014) covers 2015 WK V6 Jeeps built from July 21 through October 17, 2014. It lists improved 4-3 and 3-2 downshifts, better shift timing at altitude and in Sand mode, multi-gear downshift timing when passing, and a fix for an intermittent delayed upshift.
• 5.7L / 8HP70. The same bulletin covers Hemi Jeeps from the same build window with better upshift timing in Eco, base and Hill modes and on cruise, improved 8-7, 3-2 and 2-1 downshifts, and better converter clutch engagement. For 2014 Hemi Jeeps, bulletin 21-003-15 (January 2015) adds a complaint that looks like an electrical fault: ECO mode turns itself back on after the ignition is cycled. It also covers poor light-throttle upshifts, poor passing downshifts, weak performance on grades and at altitude, rough tip-in and tip-out with the converter clutch applied, and poor engagement in 4x4 High and Low.
• 3.0L EcoDiesel / 8HP70. Bulletin 21-045-15 (July 2015) covers a bump on light tip-in at low speed, a downshift flare when coasting at higher altitude, bumps on the 6-5 downshift and the 1-2 upshift, delayed 1st and 2nd gear upshifts, and poor shift quality in 4WD Low. It also fixes an odd one: stopped in Snow mode, pressing the plus paddle gave a 2-1 downshift instead of holding 2nd.

Every one of these bulletins sets the same rules for the flash. Put a battery charger on the Jeep and keep the voltage between 13.2 and 13.5 volts, and restart the flash if it is interrupted. They also say not to clear the shift adaptives after the flash, because the transmission may not shift smoothly until it relearns them. FCA allows 0.2 hours for most of them.

Problem 2: A Check Engine Light With No Driveability Complaint

Some V6 Jeeps show up with the MIL on and a transmission code stored, but drive fine. FCA documented this. Bulletin 21-027-15 Rev. A (August 2015) covers 2015 WK and WD vehicles with the 845RE and lists three codes that can set by mistake:

• P1DCD: TCM monitoring processor performance, multiple clutches locked up.
• P1B13: Park-By-Wire, unintended out of park position.
• P0734: gear 4 incorrect ratio.

The fix is a TCM reflash. So before you condemn a clutch pack over a P0734, check the software level and drive it with a scan tool on it. A real 4th-gear ratio fault has a symptom you can feel, and the actual input-to-output speed ratio will drift away from the commanded gear. A false code usually has neither.

The SRT has its own version. Bulletin 21-002-17 Rev. A (June 2017) covers 2017 WK SRTs with the 6.4L and 8HP70 built through May 17, 2017, for P1DCD-00 with the MIL on. The same flash fixes a limp mode that left the transmission stuck in one gear, so it now shifts while in limp-in. It also fixes bumps on the 2-1 and 6-5 downshifts while braking. Unlike the bulletins above, this one tells the tech to reset the adaptive values and run the Quick Learn under Misc Functions after the flash, and pays 0.5 hours for it. Follow the bulletin that matches the Jeep in front of you. Do not apply one bulletin's adaptation rule to the others.

Earlier SRT flashes covered harsh or inconsistent upshifts and downshifts and a delayed shift out of 6th under hard driving. Bulletin 21-018-15 (March 2015) added an erratic 1-2 upshift in cold weather and delayed engagement from Reverse to Drive. If an SRT owner complains of a cold 1-2 flare or a slow R-D, check the software first.

The WL got a flash early too. Bulletin 21-027-21 covers 2021 WL Jeeps with the 3.6L and 850RE built through August 3, 2021. It fixes a MIL with P032F (engine producing insufficient torque) and a rough 5-4 downshift, and it requires the PCM to be updated too.

Problem 3: Rollaway and the Monostable Shifter Recall

This is not a transmission failure, but it comes in as one. Early WK2 Jeeps used a monostable shift lever that springs back to center after every selection, so the lever position does not tell the driver which gear is engaged. FCA's Part 573 report for recall 16V-240 (FCA recall S27, May 2016) covers 2014-2015 Grand Cherokees with that shifter, built from July 16, 2012 through December 22, 2015, along with 2012-2014 Chargers and 300s. That is 811,586 vehicles in total. FCA said drivers who wrongly thought the vehicle was in Park could be struck by it after getting out with the engine running and the parking brake off.

The remedy was a software update that adds another safeguard against leaving the Jeep out of Park. When a WK2 owner says it "came out of Park by itself," run the VIN for this recall before you touch anything, and check for a stored P1B13 too. That Park-By-Wire code is on the false-code list in 21-027-15 Rev. A for V6 Jeeps.

Problem 4: Fluid Level, Fluid Type and Fluid Age

No dipstick, and no way to check level by feel. On the 8HP the level is set at the fill plug, with the fluid inside a narrow temperature window. ZF's Service Information 50130 for the 8HP oil change kit lays out the procedure:

1. Jeep level on the lift, in Park, parking brake set, lights, A/C and other loads off, and no limp mode active. Have a scan tool reading transmission oil temperature.
2. Start the engine. Under 30 C, let it warm. Between 30 and 50 C, hold 2,000 rpm for 30 seconds to fill the converter, then drop to idle.
3. Select P, R and D, and hold D1 and D2 for about 10 seconds each. Confirm the temperature is still 30 to 50 C.
4. Pull the fill plug. If nothing comes out, add fluid until it does, then wait for single drops and install the plug.

ZF warns that too little fluid damages the transmission, and too much goes out the overflow once the unit is hot. Never set the level above 50 C. ZF lists two fill plug sizes on the 8HP, M18 x 1.5 with an 8 mm hex at 35 Nm and M22 x 1.5 with a 10 mm hex at 30 Nm, so check which one you have. The plastic pan with the integrated filter takes 10 Nm, crosswise from the center out, with every bolt started by hand first.

Fluid: FCA's call-out for its ZF eight-speeds is Mopar ZF 8&9 Speed ATF, part number 68218925AB, or an equivalent, with a warning that the wrong fluid may affect how the transmission works (it is listed that way in bulletin 21-019-23). ZF's own product is LifeguardFluid 8. Its data sheet calls the factory fill lifetime oil, but in the same document recommends a change at 150,000 km, about 93,000 miles, and sooner for high temperature, heavy load or an unknown history. A lot of these Jeeps tow, so most of them qualify for the earlier change. ZF's instructions also say no additives of any kind. More on fill volumes and intervals is in our ZF8HP fluid type and capacity guide.

Problem 5: Valve Body Wear on High-Mileage Jeeps

If the software is current, the fluid is right and the complaint is still there, a high-mileage WK2 is usually a valve body job before it is a rebuild. Sonnax's ZF8HP45/ZF8HP70 valve body layout ties each common complaint to a specific worn bore. That covers both the 845RE in the V6 Jeeps and the 8HP70 in the Hemi, diesel and SRT:

• Bump or flare shifts, burnt clutches, lost gears, ratio or solenoid codes: clutch holding valve bores, Sonnax kit 35740-20K (five holding valve locations).
• Converter shudder, TCC slip or codes, overheated converter: TCC valve (ZF WK-V), kit 35740-13K.
• Coastdown clunk, harsh TCC apply, lining failure: TC pressure valve (ZF WD-V), kit 35740-18K.
• Harsh or soft shifts, erratic or high line pressure: pressure regulator valve (ZF SYS-DR), kit 35740-01K.

On the scan tool, compare commanded gear with the actual speed ratio during the shift, and watch converter slip once lockup is commanded. A ratio that flares and then settles on a warm unit with clean, correct-level fluid points at a holding valve. Lockup slip that grows with heat points at the TCC circuit. A ratio code with dark, burnt fluid and clutch material in the pan is not a valve body job: that transmission comes apart. Our ZF8HP valve body wear guide walks through the bench checks.

The Order I Work a Grand Cherokee Eight-Speed Complaint

1. Identify the unit from the sales code: 845RE, 8HP70 or 850RE.
2. Run the VIN for open recalls, including 16V-240 on 2014-2015 WK2s with the monostable shifter.
3. Save every TCM and engine code before you clear anything. Do not reset adaptations unless the bulletin you are applying says to.
4. Compare the TCM software level against the reflash bulletins for that engine. Flash with a charger on.
5. Set the fluid level by ZF's temperature-gated procedure, and look at the fluid on the way out.
6. If the level was low, find the leak at the pan, the cooler lines and the fill plug before you top it off.
7. If the complaint is still there with correct, clean fluid, work the valve body bores that match the symptom. Debris in the pan means a rebuild.

Frequently Asked Questions

What transmission is in a Jeep Grand Cherokee?

Most WK2 Grand Cherokees from 2014 on use a ZF-based eight-speed. The 3.6L V6 (ERB) uses the 845RE (sales code DFL), and the 5.7L Hemi, 3.0L EcoDiesel and 6.4L SRT use the 8HP70 (DFD or DFK). The 2021 WL with the 3.6L uses the second-generation 850RE (DFT), so check the sales code before ordering parts.

Why does my Grand Cherokee have a P0734 code but shift fine?

FCA bulletin 21-027-15 Rev. A says P0734, P1DCD and P1B13 can set erroneously on 2015 Grand Cherokees with the 845RE and turn on the MIL. The fix is a TCM reflash. A real 4th-gear ratio fault comes with a symptom you can feel and a speed ratio that drifts from the commanded gear.

What transmission fluid does a Grand Cherokee 8-speed take?

FCA calls for Mopar ZF 8&9 Speed ATF, part number 68218925AB, or an equivalent, and warns the wrong fluid may affect how the transmission works. ZF LifeguardFluid 8 is ZF's own fluid for the 8HP. ZF recommends a change at 150,000 km, about 93,000 miles, and sooner for towing, heat or unknown history.

Was there a recall on the Grand Cherokee shifter?

Yes. Recall 16V-240 (FCA S27) covers 2014-2015 Grand Cherokees with the monostable shifter, built July 16, 2012 through December 22, 2015, because drivers could exit thinking the vehicle was in Park. The remedy was a software update that adds another safeguard. Run a VIN recall check on any WK2 with a rollaway or park complaint.

Should I reset the transmission adaptations after a TCM flash?

Only if the bulletin says to. Most WK2 eight-speed reflash bulletins, such as 21-039-14 and 21-003-15, say not to clear the shift adaptives because the transmission may not shift smoothly until they relearn. The 2017 SRT bulletin 21-002-17 Rev. A is the exception and calls for an adaptive reset and Quick Learn.