Aston Martin Db7 U1859 Engine Trouble Code
What is Aston Martin Db7 U1859?
Aston Martin Db7 U1859 indicates potential catalytic converter failure. If completely failed, your vehicle may not run properly and fuel economy will suffer significantly. Average replacement cost is $2,000–$2,140. This repair requires professional service and should not be delayed.
U1859 on the Aston Martin Db7
A known issue on the Aston Martin Db7 is that aftermarket air filter upgrades can inadvertently trigger U1859. High-flow filters alter the intake resonance frequency, causing the MAP sensor to report pressure readings outside factory calibration.
Code Information
| Code Type: | OBD-II Network (U) Trouble Code |
| System: | Network |
| Vehicle: | Aston Martin Db7 |
| Brand: | Aston |
| Model: | Martin Db7 |
| Code: | U1859 |
U1859 Aston Martin Db7 Symptoms
Check Engine Light
Illuminated Aston Martin Db7 dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Aston Martin Db7
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Aston Martin Db7
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 Aston Martin Db7 U1859
Diagnostic Steps:
The catalytic converter has oxygen sensors before and after it. When warm and in closed-loop mode, the upstream O2 sensor reading should fluctuate, while downstream should remain steady.
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 U1859, verify VCT solenoid operation. Look for stuck or sticking valves caused by contamination. Consult vehicle-specific repair manual for proper component testing procedures.
Aston Martin Db7 U1859 Repair Cost
Ground circuit repairs on the Aston Martin Db7 — a common cause of U1859 — are labour-intensive but parts are cheap. Expect 1.5–2.5 hours of labour ($120–$200) to clean, treat, and re-torque all engine and transmission ground straps. This is excellent value given how often it resolves persistent fault codes.
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 Aston Martin Db7
The Aston Martin Db7 purge valve for the EVAP system is located in an area prone to heat damage. It is often overlooked in favour of replacing the carbon canister ($120–$200) when the valve itself ($25–$50) is the failed component for U1859.
DIY Repair Guide: U1859 on Aston Martin Db7
When attempting DIY diagnosis of U1859 on your Aston Martin Db7, a smoke machine test is the gold standard for finding vacuum leaks. Rental tools are available from most auto parts stores for $0–$20/day, or you can fabricate a makeshift tester using a hand vacuum pump and soapy water spray.
Preventing U1859 on the Aston Martin Db7
After any fuel system repair on the Aston Martin Db7, always perform a fuel-trim reset and adaptation drive. Skipping this step leaves the ECU operating on pre-repair learned values, which can generate false U1859 alerts for weeks after the fix.
Frequently Asked Questions — Aston Martin Db7 U1859
A: Yes. Any stored fault code — including U1859 — will cause an automatic failure in most OBD-II based emissions tests. The code must be resolved and the vehicle must complete a full OBD drive cycle with no new codes before the test.