Graham Saloon U1859 Engine Trouble Code
What is Graham Saloon U1859?
With Graham Saloon U1859, you may drive for several weeks with a malfunctioning MAF sensor, but expect decreased fuel economy and eventual stalling. Shop replacement costs $240–$400 depending on vehicle. The labour is straightforward, with most cost from the part itself.
U1859 on the Graham Saloon
Independent workshop data shows that Graham Saloon vehicles with U1859 resolve approximately 40% of cases after a throttle body cleaning and idle relearn procedure. This is always the recommended first step before investing in new sensors.
Code Information
| Code Type: | OBD-II Network (U) Trouble Code |
| System: | Network |
| Vehicle: | Graham Saloon |
| Brand: | Graham |
| Model: | Saloon |
| Code: | U1859 |
U1859 Graham Saloon Symptoms
Check Engine Light
Illuminated Graham Saloon dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Graham Saloon
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Graham Saloon
Increased Emissions
Failed emissions test due to U1859
U1859 Code Structure
Understanding what each digit means in the U1859 network trouble code:
| U | 1 | 8 | 5 | 9 |
|---|---|---|---|---|
| Network Code | Fuel And Air Metering | Engine Oil Temperature Sensor Malfunction | Cylinder 1 Injector Circuit Low | Reverse Input Circuit |
How to Fix Graham Saloon U1859
Diagnostic Steps:
Poor running symptoms align with MAP sensor malfunction. In some cases, a faulty MAP sensor will not trigger a code. The issue may represent separate wiring concerns requiring individual diagnosis.
Repair Solution:
Power steering pressure switch monitors system operation. If pressure changes are not detected after calibrated speed transitions, this DTC sets. Verify PSP switch operation and check for circuit opens or shorts.
Technical Notes:
U1859 DTCs can be triggered by upstream issues. For example, a dirty MAF sensor may cause incorrect fuel-trim adjustments, leading oxygen sensors to report mixture problems. Address root causes first.
Graham Saloon U1859 Repair Cost
A fuel pressure regulator replacement on the Graham Saloon runs $180–$320 at a specialist. Fuel system work requires depressurisation procedures, so this is not typically a DIY job. Some workshops include a full fuel injector flow test (value: $80) at no extra charge.
U1859 Description
U1859 engine trouble code is related to Reverse Input Circuit.
Main Cause
The primary reason for U1859 OBD-II Engine Trouble Code is: Engine Oil Temperature Sensor Malfunction.
Common U1859 Misdiagnosis on the Graham Saloon
On the Graham Saloon, the EGR cooler is sometimes replaced for U1859 when the EGR valve position sensor is at fault. The two components share a fault pathway in older scan tools that do not display live EGR valve position data.
DIY Repair Guide: U1859 on Graham Saloon
The Graham Saloon EVAP purge solenoid valve is accessible without lifting the vehicle — it is mounted on the intake manifold and secured by a single bolt and a vacuum hose clip. DIY replacement is rated 1/5 difficulty and takes approximately 20 minutes.
Preventing U1859 on the Graham Saloon
To keep the Graham Saloon free of recurring U1859 faults, change the engine oil every 5,000–7,500 miles using a grade specified by Graham. Oil viscosity directly affects VVT actuator response, and using the wrong grade is one of the most avoidable causes of this code.
Frequently Asked Questions — Graham Saloon U1859
A: Almost certainly yes. Most faults that trigger U1859 cause the ECU to operate in open-loop mode or apply overly rich fuel trims, both of which increase fuel consumption by 5–15%. Resolving the fault promptly pays for itself in fuel savings over time.