Shop All Transmission Parts →
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, P0871, P0846, and various shift-solenoid faults. The good news: on the 42RLE the solenoid pack is an external, boltable part. You do not have to pull the transmission to replace it. Drop the fluid, remove the pack, install the new one, refill. It is one of the most DIY-friendly fixes on any Chrysler automatic.
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.
42RLE Codes and What They Point To
| Code | Meaning | Most Likely Cause |
|---|---|---|
| P0700 | Transmission control system malfunction (generic) | Read the real code behind it |
| P0748 | Pressure control solenoid electrical | Solenoid pack |
| P0846 / P0871 | Pressure switch / sensor performance | Solenoid pack, low fluid |
| P0731-P0734 | Incorrect gear ratio (1st-4th) | Slipping clutch, low pressure, solenoid |
| P0720 | Output speed sensor circuit | Speed sensor |
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 with the integrated pressure sensor. Confirm your year, because early and late packs differ slightly. 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, the external solenoid pack fixes most complaints for a fraction of a rebuild cost.
42RLE Parts, Ships Same-Day
Solenoid packs, filters, ATF+4, speed sensors, coolers, and converters for the 42RLE. Our companion shop stocks the exact parts that fix limp mode and harsh shifts. Same-day ship before 2pm Eastern.
Shop Gearbox Insider →FAQ
Can I replace the 42RLE solenoid pack myself?
Yes. It is an external part bolted to the valve body. Drop the fluid, 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.