Your Grand Cherokee, Dakota, or Ram feels fine cold, then after it warms up it starts flaring, banging the 1-2, hunting for a gear, or it just drops into second and stays there no matter how fast you go. Cycle the key and it drives normally for a few minutes, then does it again. On a 42RE or 44RE that pattern almost always points to one spot: the governor pressure solenoid and its pressure sensor, both living on the valve body. Here is how to confirm it and fix it right the first time.
What the governor pressure system actually does
Unlike the fully computer-shifted units that came later, the RE-family transmissions (40RE, 42RE, 44RE, 46RE, 47RE, 48RE, roughly 1993-2007 Dodge, Ram and Jeep) use a hydraulic governor circuit that the computer modulates. The governor pressure solenoid and the governor pressure sensor both mount to the valve body transfer plate. The solenoid meters governor pressure up as road speed climbs; the sensor reads that pressure back and reports it to the transmission computer. The computer constantly compares the pressure it commanded against the pressure the sensor sees. When those two numbers disagree, it assumes something is wrong and drops the transmission into limp-in mode to protect it.
Symptoms that point at the governor circuit
- Limp mode / stuck in second. The most recognizable RE failure: the unit locks in a single gear (commonly 2nd, sometimes a 3rd-gear start) with no shifting, so the truck feels gutless.
- Warm-up dependent misbehavior. Fine when cold, erratic once the fluid heats and thins — a classic sign of a solenoid sticking or a screen partially plugged with debris.
- Harsh, abrupt shifts and delayed engagement. Per the P0748 code description, this fault produces forceful shifts, a delay when you select Drive, and a refusal to upshift.
- No overdrive / no lockup feel. Once the unit is in fault, it won't complete its normal shift schedule.
Read the codes — they tell you which half failed
These transmissions set very specific governor codes. Pull them before you touch anything. Per TRNW's 42RE diagnostic code list, the ones that matter here are:
- P0748 — Pressure Solenoid Control / Trans Relay Circuits (the solenoid's electrical side)
- P1756 — Governor Pressure Not Equal to Target @ 15-20 PSI
- P1757 — Governor Pressure Above 3 PSI In Gear @ 0 MPH
- P1762 — Governor Pressure Sensor Offset Volts Too Low or High
- P1763 — Governor Pressure Sensor Volts (out of range)
Roughly speaking, a P0748 leans toward the solenoid (electrical control), while the P1756/P1757/P1762/P1763 family leans toward the sensor reading wrong or the solenoid sticking so pressure never matches target. In practice, when one goes the other is usually not far behind, which is why the smart repair replaces both together.
Causes: it is usually contamination, not a dead transmission
The good news is that a limp-mode RE is often a cheap fix, not a rebuild. The common causes behind these codes, per the P0748 technical writeup, are dirty or degraded fluid clogging the solenoid's screen, damaged wiring or a corroded connector, or an internal solenoid coil failure. Only rarely is it the computer itself. That is why the correct first step is checking fluid condition and the external harness before condemning the unit — sticky, contaminated fluid can make a good solenoid act failed.
The fix: which part, and why
The durable repair is to replace the governor pressure solenoid and the governor pressure sensor as a pair, clean or replace the screen, and get fresh fluid in the unit. Rebuilders sell this as a matched kit — for example, the TransGo TF-GOV-SOL governor pressure solenoid repair kit is built specifically for these RE units. Doing both halves at once keeps the commanded-vs-sensed comparison honest and keeps you from being back under the truck in a month for the other component.
If the valve body itself is worn — high mileage, a history of overheating, or you're already chasing pressure-related complaints — the better move is a fresh, updated valve body rather than chasing individual bores. Sonnax notes their Zip Kit (46-47RHE-ZIP for the larger RE bodies) targets the root cause of multiple complaints by sealing the critical main-line, converter, and throttle pressure circuits that leak down as these bodies age. A properly reconditioned and dyno-tested valve body drops that whole problem in at once.
Order the RIGHT part — sensor type and pump inlet matter
This is where most people order the wrong piece. Per Sonnax's 42RE/46RE/47RE valve body identification guide, you must match two things: the pressure sensor type and the pump inlet size. There are two sensor generations. The early sensor (1999 and earlier) has an oval-shaped electrical connector; the late sensor (2000 and later) is plastic with a rectangular connector. Sonnax splits their reman 42RE bodies accordingly — part numbers CHR110/CHR111 cover the '99-and-earlier early-sensor units and CHR112/CHR113 cover the '00-and-later late-sensor units, further divided by small vs. large pump inlet. Translation: know your year and look at the connector shape before you buy, whether you're buying the solenoid, the sensor, or a complete valve body. Our valve bodies and solenoids are listed by year range so you land on the correct sensor generation.
Replace-while-you-are-in-there
The pan is already off and the fluid is already out, so knock out the wear items now:
- Governor pressure solenoid AND sensor together (never just one)
- Transmission filter and a fresh pan gasket
- Fresh, spec-correct fluid to the proper level
- Inspect and clean the solenoid screen; look for metal or clutch material in the pan
- Check the external harness connector for corrosion or a spread pin — a bad connection mimics a failed solenoid
Cost and effort
This is one of the more DIY-friendly RE repairs. The governor solenoid and sensor are accessible with the pan dropped — no case-splitting, no removing the transmission. Budget roughly 1.5 to 2.5 hours in the driveway for the solenoid-and-sensor job plus a fluid and filter service; a full valve body R&R adds a bit more time for careful bolt sequencing and re-torquing. Difficulty is moderate: if you can drop a pan and keep your parts organized, you can do this. Compared with a rebuild or a replacement unit, fixing the governor circuit is the definition of a high-value repair when the codes point here.
FAQ
Can I just replace the sensor and skip the solenoid? You can, but it's a false economy. The computer judges the unit by comparing commanded solenoid pressure to sensed pressure. If either half is marginal you'll be back in limp mode. Replace both while the pan is down.
Will the wrong-year part physically bolt on? Sometimes it will bolt up and still be wrong — the early and late sensors use different connectors and the bodies use different pump inlets. Match your year and connector shape per the Sonnax identification guide before ordering.
My truck drives fine cold but limps when hot. Is that really the governor? That warm-up pattern is textbook for a sticking solenoid or a screen fouled with debris. It's the single most common way these units fail, and it's exactly what a solenoid-and-sensor service addresses.
Sources
- Sonnax — Chrysler 42RE, 46RE, 47RE Valve Body Identification (early vs. late sensor, pump inlet, CHR part numbers)
- Sonnax — Zip Kit 46-47RHE-ZIP (sealing valve body pressure circuits)
- TransGo — TF-GOV-SOL Governor Pressure Solenoid Repair Kit
- iCarsoft — P0748 Pressure Control Solenoid 'A' Electrical (symptoms, causes, limp mode)
- TRNW — 42RE Diagnostic Trouble Code Definitions (P0748, P1756, P1757, P1762, P1763)