42RLE Transmission
Problems & Fixes

The 42RLE is a rear-wheel-drive, electronically controlled 4-speed automatic Chrysler introduced in 2003. You will find it behind the 3.7L and 4.0L in the Jeep Wrangler (TJ and JK), Liberty KJ/KK, Dodge Nitro, Chrysler 300 (base 2.7L), Dodge Charger/Magnum base models, and more. It is a decent transmission that gets a bad reputation almost entirely because of two things: an overworked solenoid pack and marginal factory cooling in trucks that tow or wheel.

Most 42RLE complaints trace back to a handful of specific failures. Diagnose the actual fault before you spend money. A P0700 by itself tells you nothing except "the transmission controller set a code" and points you to read the real code stored behind it.

The Most Common 42RLE Problems

1. Solenoid Pack Failure (the big one)

The 42RLE integrates its shift solenoids and the transmission range/pressure sensors into one serviceable solenoid pack bolted to the valve body. When it degrades you get limp mode, harsh or missing shifts, no torque converter lockup, and codes like P0700, P0748 (pressure control solenoid electrical), P0846 and P0871, and various shift-solenoid faults. The good news: the pack is a bolt-on part. Unlike the front-drive 41TE, where the pack sits on the outside of the case, the 42RLE pack is inside the pan on the valve body. You still do not have to pull the transmission: drop the pan, remove the pack, install the new one, refill.

Know which unit you have before you order. Transmission Digest's TASC Force column describes the 42RLE as the rear-drive version of the 41TE, and notes that the late 42RLE-VLP adds a line pressure solenoid and a line pressure sensor to the valve body. You can spot one by the second pass-through connector next to the range sensor connector on the case. Per Sonnax, early versions have 6 pins and later ones 5. The VLP valve body, transfer plate, separator plate and pressure regulator valve do not interchange with non-VLP parts.

On VLP units, a P0869 (line pressure too high) right after the 2-3 shift is a known pattern failure of the TCM/PCM, according to Transmission Digest. On a good unit, desired and actual line pressure track each other: about 135 psi in first and second, then about 85 psi after the 2-3 shift. Test before you replace the solenoid.

2. Limp Mode / Stuck in Second Gear

When the controller sees an electrical or pressure fault it drops the trans into a fail-safe (usually the equivalent of second gear plus reverse) to get you home without damage. The truck feels gutless and will not upshift. This is a symptom, not a failure in itself. Scan for the stored code, and 80% of the time the answer is the solenoid pack or the input/output speed sensors.

3. Overheating and Cooked Fluid

The factory cooling on a Wrangler or Liberty is marginal for towing, big tires, low-range crawling, or sustained highway heat. Burnt fluid destroys the clutch packs and the solenoid pack alike. If your fluid smells burnt or is brown, you are already losing life. Add an auxiliary transmission cooler and get back on a fresh ATF+4 fill.

4. Torque Converter Lockup Shudder

A shudder or buck at light throttle around 40-55 mph is the lockup clutch slipping. On a high-mileage 42RLE this often means the converter, and the debris it sheds is what kills the next solenoid pack. Replace the converter, do not just flush.

5. Input/Output Speed Sensor Faults

Bad or intermittent speed sensor signals throw the controller into limp mode and set shift-timing codes. These sensors are cheap and external. Rule them out before condemning anything internal. One trap after a trans swap: Transmission Digest reports that if the harness is not secured to the case, the input and output speed sensor plugs can be crossed. The truck shuttles 1-2 in drive, then failsafes with a first-gear ratio code. On the scan tool, the OSS reads RPM at startup while the ISS stays at 0. The OSS plug has a yellow tag on the harness.

Range sensor codes deserve the same scrutiny. Transmission Digest documented a 2010 Liberty 3.7L with a hard P0706 that survived a new range sensor. The real fault was an oxidized, frayed connector on the T1 circuit, fixed with Mopar connector repair kit 05017116AA.

42RLE Codes and What They Point To

The 42RLE uses ATF+4 only. Do not put Dexron in it. The friction characteristics are wrong and it will shudder and shift poorly. This matters more on Chrysler units than almost any other brand.

What to Buy by Problem

Solenoid Pack

The single most common 42RLE repair. Buy the complete pack for your year. On VLP units, the line pressure solenoid and sensor are separate parts from the pack, so diagnose which one is at fault. This alone fixes the majority of limp-mode and harsh-shift complaints.

Check 42RLE solenoid packs

Filter and ATF+4 Service Kit

Filter, pan gasket, and genuine ATF+4. Service every 30k, sooner if you tow or wheel. This is the cheapest way to keep a 42RLE alive.

Check 42RLE filter kits

Auxiliary Transmission Cooler

If you tow, run big tires, or crawl, this is not optional. A stacked-plate cooler mounted in front of the condenser drops fluid temps 30-50 degrees and is the best money you will spend on this transmission.

Check transmission coolers

Input / Output Speed Sensors

Cheap, external, and a frequent cause of intermittent limp mode. Worth replacing as a pair on a high-mileage unit throwing speed-sensor codes.

Check 42RLE speed sensors

Diagnose It Right the First Time

• Scan for the stored code, not just P0700. A basic reader may only show P0700. Use a scanner that reads Chrysler transmission-specific codes.
• Check the fluid first. Level, color, smell. Low or burnt fluid mimics every electronic fault on this trans.
• Confirm it is ATF+4. The wrong fluid causes shudder and shift complaints that look like hardware failure.
• Wiggle-test the connectors. Solenoid pack and speed-sensor connectors corrode. Intermittent limp mode is often a bad connection.
• Replace the pack before the rebuild. On a 42RLE, a pan-drop solenoid pack swap fixes most complaints for a fraction of a rebuild cost.

FAQ

Can I replace the 42RLE solenoid pack myself?

Yes. On the 42RLE it is bolted to the valve body inside the pan. Drop the pan, unbolt the old pack, install the new one, and refill with ATF+4. No transmission removal, no teardown. It is one of the easier Chrysler repairs.

Why is my 42RLE stuck in one gear?

That is limp mode. The controller detected a fault and defaulted to a fail-safe gear. Scan for the real stored code, check fluid, and inspect the solenoid pack and speed sensors before assuming the worst.

What fluid does the 42RLE take?

ATF+4 only. Never Dexron or a generic multi-vehicle ATF. The wrong fluid causes shudder and poor shifts that get misdiagnosed as mechanical failure.

Is the 42RLE a reliable transmission?

Reasonably, if you keep the fluid fresh and the temperature down. Add a cooler if you tow or wheel, service it on schedule, and the solenoid pack is the only recurring headache.