B1342: How to Diagnose & Fix — ECU / Control Module Is Defective
5 vehicles · 1 makes · $30-$1,200 repair
How to diagnose and fix B1342: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Ford Transit · 2015–2020
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 Special Service Message 47094 notes that 2015-2017 Transits may fail BCM installation programming when a new body control module is installed.
Common Symptoms
- Random door locks cycling or activating on their own
- Instrument cluster warning lights illuminating without cause
- Power windows or accessories becoming inoperative intermittently
- Battery drain or parasitic draw
- Multiple unrelated fault codes stored across modules
How to Fix
Diagnose with Ford IDS/FDRS scan tool to identify BCM fault codes. If water intrusion is present, address the leak source first. BCM replacement (Ford part number varies by configuration, ~$300–$500 OEM) and programming/configuration to the vehicle using Ford PATS and IDS is required. In some cases, a BCM software update alone resolves the issue.
Sources for this issue (1)
Ford Bronco Sport · 2021–2024
A defect in the SYNC 3 infotainment software (APIM module) on 2021-2024 Bronco Sport vehicles causes system instability. Symptoms include the display intermittently going black, failure to retain settings across ignition cycles (reverted language, erased radio presets), and inability to install updates. A separate SYNC 3 software error can leave the rearview/backup camera showing a blank image while in reverse or keep the camera image on screen after backing has ended, which is a federal rear-visibility safety concern.
Common Symptoms
- Infotainment screen goes black or freezes
- Lost radio presets and reverted language/settings after restart
- Backup camera shows a blank/blue/black image
- Camera image remains on screen after shifting out of reverse
- Inability to install software updates
How to Fix
Addressed by two Ford programs: a 2024 field service action / Customer Satisfaction Program (24B47) APIM software reconfiguration for the instability/lost-settings symptoms, and safety recall 25S72 / NHTSA 25V442 for the blank/persistent backup camera image (a SYNC 3 software flash of the APIM, ~34,597 Bronco Sports). Both fixes are free at a Ford dealer.
Sources for this issue (2)
Ford Focus · 2008–2018
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.
Common Symptoms
- Door ajar warning on dash with all doors closed
- Interior lights stay on after locking
- Battery drain overnight
- Door ajar chime sounds while driving
- Alarm triggered by false door open signal
How to Fix
Replace the door latch assembly containing the failed ajar switch. OEM latch assemblies cost $50-100; aftermarket versions are $30-60. Replacement takes 30-60 minutes and requires removing the door panel. As a temporary fix, the interior light fuse can be pulled to prevent battery drain, or the dome light switch can be set to the off position. Spraying WD-40 into the latch mechanism can temporarily restore the switch contact but is not a permanent fix.
Sources for this issue (2)
Ford Escape · 2008–2011
Ford F-150 · 2013–2020
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B1342 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 B1342 mean?
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.
What are the most common causes of B1342?
The most common causes of B1342 are: 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. The specific cause varies by vehicle.
How much does it cost to fix B1342?
Repair costs for B1342 range from $30 to $1,200, depending on the vehicle and root cause.
Which vehicles are affected by B1342?
Au7o has documented B1342 across 5 vehicle models from 1 manufacturers: Ford.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.