U0101 on Chrysler: Causes, Symptoms and Fix Cost
Quick Answer
Not safe to drive
U0101 on a Chrysler means one or more control modules have stopped receiving messages from the transmission control module (TCM), the computer that decides when an automatic or dual-clutch gearbox shifts. The code is stored by the module that lost contact, so it describes a communication problem rather than a worn gearbox. The TCM may have lost power or ground, the network wiring may be damaged, or the TCM itself may have failed.
- Severity
- High · Electrical
Connect a standard OBD2 adapter (Bluetooth LE on iPhone) to your Chrysler and Skanyx tells you what U0101 means on that engine, whether it is safe to keep driving, and what the fix should cost. Free on iPhone and Android.
Get Skanyx freeWhat does U0101 mean on a Chrysler?
The Quick Answer above is the generic definition. What follows is the model-specific detail for the Chrysler models that log U0101.
Chrysler 300 (LX, 5.7 V8 with 722.6 gearbox)
2005-2010
A transmission-rebuilder case file (ATSG) records a 2005 Chrysler 300 with the 5.7 V8 and the 722.6 (NAG1) five-speed automatic where the engine, ABS and body computers all showed U0101. The TCM had no power with the key on because the NAG1 diode in its supply had been fitted the wrong way round. It is one documented case, so check the TCM power feed first on this model.
Source: trnw.net
Sources
- trnw.net trnw.net/images/sponsors/ads/ATSG_Confirmed_Fix_December2021.htm
What causes U0101 on a Chrysler?
Beyond the generic causes listed on the main U0101 page, these are the patterns noted for Chrysler models:
NAG1 diode fitted backwards or faulty in the TCM power feed
: Chrysler 300 (LX, 5.7 V8 with 722.6 gearbox)
Faulty transmission relay or fuse in the TCM supply
: Chrysler 300 (LX, 5.7 V8 with 722.6 gearbox)
How to diagnose U0101 on a Chrysler with OBD2
- Test the battery and charging first. A rested battery should read about 12.4V or more, and a weak one can set communication codes in several modules at once.
- Read every module with a scanner that reaches them all (a generic OBD2 reader usually sees only the engine and sometimes the gearbox computer). Note which modules store U0101: one reporter points to that module's wiring, while many reporters point to the TCM or the shared bus.
- Look up the TCM fuses and power relay in the wiring diagram and check them, including the ignition-fed and the battery-fed feeds.
- Inspect the TCM connector for corrosion, bent pins or green deposits, and look at the harness for rubbed or water-soaked sections.
- With the ignition on, measure the TCM supply and earth pins under load. Voltage drop on the earth side should be tiny, around 0.1V.
- With the ignition off and the car asleep, measure resistance between pins 6 and 14 of the diagnostic socket. About 60 ohms is normal for a CAN bus with both end resistors present.
- Compare the gearbox type before blaming the TCM: on some dual-clutch and conventional automatics the TCM sits on or inside the gearbox, so oil leaks and heat can reach it.
- Replace the TCM only after power, earth and the network pass, and expect it to need programming to the car.
How much does U0101 cost to fix on a Chrysler? (EUR)
Estimated repair costs for U0101 in EUR, compiled across makes. Expect Chrysler parts and labour towards the upper end of each range.
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Battery replacement or terminal and earth cleaning | €0–€200 | €0–€60 | €0–€260 | Easy |
| Replace blown TCM fuse or power relay | €5–€100 | €10–€60 | €15–€160 | Easy |
| Repair CAN wiring or TCM connector pins | €10–€60 | €80–€250 | €90–€310 | Moderate |
| Transmission control module diagnosis and repair | €100–€500 | €80–€250 | €180–€750 | Professional |
| Replace TCM with programming | €300–€1000 | €150–€350 | €450–€1350 | Professional |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
Codes related to U0101
These codes are often seen alongside U0101 or point to related issues, on any make:
Looking for the full U0101 reference (all makes, full diagnosis flow, complete repair cost matrix)? See the main U0101 guide