B1342 on Ford
ECU / Control Module Is Defective
B1342 on Ford vehicles indicates ecu / control module is defective. Au7o has documented this code across 3 Ford models — most commonly on Focus, Mustang, Transit. This is a manufacturer-specific body code (common on Ford and other makes) generally meaning a control module has detected an internal fault and considers itself defective. It can be set by a true internal hardware/software failure of the module or, very often, by power and ground problems such as low battery voltage that make the module behave abnormally. Because the symptoms depend on which module set it, behavior varies widely. Before replacing any module, supply voltage, grounds, and connections should be verified first. Typical repair costs on Ford range from $30 to $1,400, depending on the specific model and root cause.
Common Causes of B1342
- •Low or unstable battery/system voltage
- •Poor power or ground connection to the module
- •Corroded or loose module connectors
- •Corrupted module software/configuration
- •Internal module hardware failure
- •Recent electrical work or battery disconnection issues
B1342 on Ford by Model
Ford Focus(1 issue)
- Door Ajar Warning False Alarm and Interior Lights Staying On2008-2018
The Focus door ajar switch integrated into the door latch assembly fails, causing the dash to display a door ajar warning when all doors are closed. This also keeps the interior dome lights on, which drains the battery overnight. The latch switch corrodes or wears out, sending a false open signal to the body control module. Any of the four doors can be affected, though the driver door is most common.
Ford Mustang(1 issue)
- 2005-2010 Smart Junction Box Water Intrusion Causing Wiper, Lighting, and Electrical Malfunctions2005-2010
S197 Mustangs are known to suffer from water intrusion at the cowl/windshield area that reaches the Smart Junction Box (SJB)/fuse box, leading to erratic electrical behavior. Owners report inoperative or self-activating wipers, lighting faults, battery drain, no-start conditions, and multiple unrelated electrical issues after rain or car washes. Ford published service information addressing water leak diagnosis and SJB-related corrosion concerns on these cars.
Ford Transit(1 issue)
- Body Control Module (BCM) Failure Causing Intermittent Electrical Gremlins2015-2020
Ford Transit BCMs, particularly on 2015–2019 models, have been reported to fail or develop software faults causing a wide array of seemingly unrelated electrical issues including random door lock cycling, instrument cluster malfunctions, and accessory power loss. Water intrusion from sunroof drains or cowl leaks can accelerate BCM failure by corroding the module's internal connectors. Ford TSB 18-2175 acknowledged BCM programming faults contributing to some of these behaviors.
Looking for B1342 on a different make?
View B1342 across all makes →Frequently Asked Questions
What does B1342 mean on Ford?▼
B1342 stands for "ECU / Control Module Is Defective." This is a manufacturer-specific body code (common on Ford and other makes) generally meaning a control module has detected an internal fault and considers itself defective. It can be set by a true internal hardware/software failure of the module or, very often, by power and ground problems such as low battery voltage that make the module behave abnormally. Because the symptoms depend on which module set it, behavior varies widely. Before replacing any module, supply voltage, grounds, and connections should be verified first. On Ford specifically, this code is documented across 3 models.
What causes B1342 on Ford vehicles?▼
Common causes on Ford: Low or unstable battery/system voltage, Poor power or ground connection to the module, Corroded or loose module connectors, Corrupted module software/configuration, Internal module hardware failure. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix B1342 on a Ford?▼
Repair costs on Ford range from $30 to $1,400, depending on the specific model and root cause.
Which Ford models have B1342 documented?▼
Au7o has documented B1342 on 3 Ford models: Focus, Mustang, Transit.