Plymouth Valiant B1805 Engine Trouble Code
What is Plymouth Valiant B1805?
The Plymouth Valiant B1805 check-engine light can indicate issues ranging from minor (loose gas cap) to serious (catalytic converter failure). Professional diagnostic scanning at a dealer or shop will identify the exact cause and required repairs.
B1805 on the Plymouth Valiant
Diesel variants of the Plymouth Valiant trigger B1805 most often due to swirl flap actuator failure. The plastic actuator arm breaks and the flap defaults to the closed position, causing severe intake restriction and the associated fault flag.
Code Information
| Code Type: | OBD-II Body (B) Trouble Code |
| System: | Body |
| Vehicle: | Plymouth Valiant |
| Brand: | Plymouth |
| Model: | Valiant |
| Code: | B1805 |
B1805 Plymouth Valiant Symptoms
Check Engine Light
Illuminated Plymouth Valiant dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Plymouth Valiant
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Plymouth Valiant
Increased Emissions
Failed emissions test due to B1805
B1805 Code Structure
Understanding what each digit means in the B1805 body trouble code:
| B | 1 | 8 | 0 | 5 |
|---|---|---|---|---|
| Body Code | Fuel And Air Metering | Engine Oil Temperature Sensor Malfunction | Cold Start Injector 1 Malfunction | Crankshaft Position Sensor B Circuit Malfunction |
How to Fix Plymouth Valiant B1805
Diagnostic Steps:
Check if fuel pump primes when key is turned to ON. Measure fuel pressure and verify bright white-blue spark at all plugs. Also verify mechanical timing alignment.
Repair Solution:
Most manufacturers number cylinders sequentially from front to back. Ford V-engines start with cylinder 1 at front left. In V-6 engines, cylinder 4 is front right; in V-8 engines, cylinder 5 occupies that position.
Technical Notes:
For B1805, verify VCT solenoid operation. Look for stuck or sticking valves caused by contamination. Consult vehicle-specific repair manual for proper component testing procedures.
Plymouth Valiant B1805 Repair Cost
A complete diagnostic health-check on the Plymouth Valiant before committing to any single repair costs $120–$180 at a dealership with live-data capability. This investment pays for itself if it prevents unnecessary part replacement, which is the single most common mistake when diagnosing B1805.
B1805 Description
B1805 engine trouble code is related to Crankshaft Position Sensor B Circuit Malfunction.
Main Cause
The primary reason for B1805 OBD-II Engine Trouble Code is: Engine Oil Temperature Sensor Malfunction.
Common B1805 Misdiagnosis on the Plymouth Valiant
On Plymouth Valiant vehicles, the turbo boost solenoid and the MAP sensor feed into the same diagnostic path. B1805 caused by a faulty boost solenoid is sometimes charged to the customer as a MAP sensor replacement, doubling unnecessary parts spend.
DIY Repair Guide: B1805 on Plymouth Valiant
The fuel pressure test on the Plymouth Valiant requires a Schrader-valve type fuel pressure gauge ($25–$40) connected to the fuel rail test port. With the ignition ON (engine off), pressure should hold above 30 PSI for two minutes. A rapid drop confirms a leaking injector or failing regulator as the root cause of B1805.
Preventing B1805 on the Plymouth Valiant
Keeping the Plymouth Valiant battery in good health — testing specific gravity annually and replacing at first sign of degradation — protects the ECU voltage supply. Voltage drops during cranking cause sensor reading spikes that can spuriously store B1805.
Frequently Asked Questions — Plymouth Valiant B1805
A: Yes. Some fault conditions, particularly those involving EVAP system leaks or marginal sensor readings, store codes without producing noticeable drivability symptoms. These are called memory faults and still need to be addressed because they will eventually cause performance issues.