U1842 Cadillac Code - Lost Communication With ECM/PCM
Quick Answer
The system voltage is between 9-16 volts. Common causes include Faulty Engine Control Module (ECM)/Powertrain Control Module (PCM), Engine Control Module /Powertrain Control Module harness is open or shorted, Engine Control Module /Powertrain Control Module circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- U1842 Cadillac indicates Lost Communication With ECM/PCM.
- Common causes
- Common causes include Faulty Engine Control Module (ECM)/Powertrain Control Module (PCM), Engine Control Module /Powertrain Control Module harness is open or shorted, Engine Control Module /Powertrain Control Module circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code U1842 Cadillac Description
What are the Possible Causes of the DTC U1842 Cadillac?
- Faulty Engine Control Module (ECM)/Powertrain Control Module (PCM)
- Engine Control Module /Powertrain Control Module harness is open or shorted
- Engine Control Module /Powertrain Control Module circuit poor electrical connection
How to Fix the DTC U1842 Cadillac?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the U1842 Cadillac code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about U1842 Cadillac Code
1. What does OBDII code U1842 mean on a Cadillac?
It means there is a communication failure between the Engine Control Module (ECM) and other control modules on the vehicle's network.
2. What are common symptoms of code U1842 in a Cadillac?
Symptoms may include the check engine light turning on, reduced engine performance, erratic shifting, or failure to start.
3. What can cause the U1842 code to appear?
Possible causes include damaged wiring, faulty connectors, a malfunctioning ECM or PCM, or network communication issues.
4. Can a weak battery cause the U1842 code?
Yes, a weak or failing battery can disrupt communication between modules and trigger this code.
5. How is the U1842 code diagnosed?
A technician will use a scan tool to check for network communication, inspect wiring and connectors, and test the ECM and other modules for proper functionality.
6. Can I drive my Cadillac with the U1842 code?
Driving may be possible, but it’s not recommended as the vehicle could exhibit reduced performance or additional issues.
7. How do I fix the U1842 code on a Cadillac?
Repairs may involve replacing damaged wiring, repairing connectors, reprogramming the ECM, or replacing a faulty module.
8. Is the U1842 code specific to Cadillacs?
No, the U1842 code can appear in various makes and models, but its diagnosis and repair may vary slightly depending on the vehicle.
9. Will clearing the U1842 code fix the issue?
Clearing the code may temporarily turn off the warning, but the underlying issue must be resolved to prevent the code from returning.
10. How much does it cost to repair the U1842 code?
The cost depends on the specific issue but can range from $100 for minor wiring repairs to over $1,000 if a module needs replacing.
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