P0645 on Dodge: How to Diagnose & Fix
A/C Clutch Relay Control Circuit
1 Dodge model · 1 documented issue · 1 critical
P0645 on Dodge by model: symptoms, diagnosis and fix
The Dodge Challenger has a well-documented tendency to stall or shut off completely without warning while driving — a top-3 engine-category complaint at NHTSA and one of the most-reported electrical/engine problems at CarComplaints. There are two primary, separately documented root causes that present the same symptom. (1) ALTERNATOR FAILURE (3.6L Pentastar, and later 5.7L/6.4L with electro-hydraulic power steering). Chrysler began investigating stalling complaints on 2011-2012 Dodge Chargers in August 2014 and found thermal fatigue of the silicon diodes inside the alternator. The large, intermittent current draw of the electro-hydraulic power-steering (EHPS) pump thermally stresses the diodes until the alternator fails suddenly. This became NHTSA recall 14V634 (Chrysler P60), covering ~434,000 2011-2014 Chrysler 300, Dodge Charger, Challenger, Durango, and 2012-2014 Jeep Grand Cherokee vehicles with the 3.6L engine and 160-amp alternator (remedy began Feb 27, 2015). It was later expanded under NHTSA recall 17V435 (remedy began Feb 12, 2018) to additional 2011-2014 cars with EHPS and 5.7L or 3.6L engines. NHTSA's stated consequence for both: "If the alternator fails, the vehicle may stall without warning, increasing the risk of a crash," with an additional risk of an underhood fire from a short circuit. (2) TIPM (Totally Integrated Power Module) / FUEL-PUMP-RELAY FAILURE (2008-2014, all engines). The TIPM is the car's central fuse/relay/electrical-distribution computer. When it (or its internal fuel-pump relay) degrades, owners report the engine stalling or shutting off mid-drive, intermittent no-starts, flickering lights, and multiple simultaneous warning lights (check engine, traction control/ESC, ABS). CarComplaints documents this on the 2009 Challenger ("engine shuts down while driving," 7 complaints, severity 8.6/10, ~$800 average repair, ~43,300 miles) and the 2013 Challenger ("bad TIPM," 12 complaints, severity 7.2/10, ~$940 average repair, ~43,050 miles). Because the engine quits unexpectedly, the driver loses power steering and (on automatics) power braking assist while the car is in motion — making this a genuine safety hazard, especially in intersections, on highway merges, and during turns. Multiple NHTSA complaints describe near-crashes and crashes from sudden loss of power.
Common Symptoms
- Engine suddenly shuts off / stalls while driving with no warning
- Stalling during turns, merging, or in intersections (loss of power steering and brake assist)
- Battery / charging-system warning light, then dimming or flickering headlights and dash lights (alternator)
- Multiple warning lights at once (check engine, traction control/ESC, ABS)
- Intermittent no-start or having to cycle the ignition several times to start
- Engine cranks but won't fire after a stall
- Random electrical glitches (lights flashing, wipers activating, alarm cycling) before the stall (TIPM)
- Hesitation or loss of acceleration before shutdown
How to Fix
First, check open recalls by VIN at nhtsa.gov/recalls or with a Dodge dealer — 2011-2014 3.6L cars (and EHPS 5.7L/6.4L cars) are covered by alternator recalls 14V634 / 17V435, which replace the alternator FREE of charge. If your car qualifies, this is the cheapest and correct fix. For the alternator path off-recall: a charging-system test (battery, alternator output, voltage drop at the alternator plug/ground) confirms the failure. Watch for the battery/charge warning light, dimming lights, and a P0562 (system voltage low) DTC before a full stall. Replace the alternator (3.6L commonly uses a 160A or 220A unit) and inspect the wiring connector and ground for corrosion/damage, since a bad plug or ground can mimic a failed alternator. For the TIPM path: have the TIPM and its internal fuel-pump relay tested. A common, far cheaper interim fix for the fuel-pump-relay failure mode is an external fuel-pump relay bypass kit that takes the load off the failing internal relay (~$50-120 part). The full fix is replacing/rebuilding the TIPM — replacement modules run roughly $500-900 plus programming/labor, or a specialist rebuild is often more cost-effective. Inspect/clean grounds and check for water intrusion into the module. Confirm the diagnosis before throwing parts at it: scan for DTCs, monitor charging voltage with the engine running (should be ~14.1-14.4 V), and note whether the stall is preceded by electrical glitches (TIPM) or a charge/battery warning (alternator).
Sources for this issue (1)
P0645 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0645 mean on a Dodge?
P0645 stands for "A/C Clutch Relay Control Circuit." A general fault in the A/C compressor clutch relay control circuit driven by the control module. The commanded relay state does not match the measured circuit condition. On Dodge it is documented across 1 model: Challenger.
What are the most common causes of P0645?
The most common causes of P0645 are: Faulty A/C clutch relay, Open or short in the relay control circuit, Corroded/damaged connectors, Blown fuse, Internal PCM driver fault. The specific cause varies by vehicle.
How much does it cost to fix P0645 on a Dodge?
Repair costs vary widely with the root cause and Dodge model; each issue on this page carries its own estimate where one is published.
Looking for P0645 on a different make?
View P0645 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.