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P1935 Mercury Code - Fuel Additive Level Low

Quick Answer

The P1935 diagnostic trouble code for Mercury vehicles indicates that the fuel additive level is low. Common causes include Low DEF fluid level in the tank, DEF tank sensor malfunction, DEF injector malfunction. 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
P1935 Mercury indicates Fuel Additive Level Low.
Common causes
Common causes include Low DEF fluid level in the tank, DEF tank sensor malfunction, DEF injector malfunction.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 14, 2024
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Code P1935 Mercury Description

The P1935 diagnostic trouble code for Mercury vehicles indicates that the fuel additive level is low. This code is typically associated with vehicles equipped with a diesel engine that utilizes a selective catalytic reduction (SCR) system. The SCR system requires a specific type of diesel exhaust fluid (DEF), also known as AdBlue, to reduce harmful emissions. When the fuel additive level is low, it can lead to increased emissions and reduced efficiency of the SCR system.

OBDII Code P1935 Mercury - Fuel Additive Level Low
P1935 Mercury Code - Fuel Additive Level Low

Common Causes of P1935 Mercury

  1. Low DEF fluid level in the tank.
  2. DEF tank sensor malfunction.
  3. DEF injector malfunction.
  4. Wiring issues or electrical faults.
  5. Contamination of DEF fluid.

Symptoms of P1935 Mercury

  1. Illumination of the check engine light on the dashboard.
  2. Reduced fuel efficiency.
  3. Increased emissions.
  4. Potential compliance issues with emissions regulations.
  5. Reduced performance of the SCR system.

How to Fix P1935 Mercury

  1. Check the DEF fluid level in the tank and refill if necessary.
  2. Inspect the DEF tank sensor for proper operation and replace if faulty.
  3. Check the DEF injector for clogs or malfunctions and clean or replace as needed.
  4. Inspect the wiring and electrical connections related to the SCR system for any faults and repair as necessary.
  5. Ensure that the DEF fluid is not contaminated and replace if needed.

Cost to Fix P1935 Mercury

The typical repair costs for addressing a P1935 code related to low fuel additive level can vary depending on the specific cause of the issue. In general, the cost of DEF fluid is relatively affordable, ranging from $10 to $30 for a 2.5-gallon container. If the issue is related to a faulty sensor, injector, or wiring, the cost of parts and labor could range from $200 to $500 or more. It is advisable to consult with a qualified mechanic or dealership to obtain a more accurate estimate based on the specific circumstances of the vehicle. Labor rates at auto repair shops can vary, typically ranging from $80 to $150 per hour, so it's essential to consider these factors when estimating repair costs.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1935 Mercury Code

1. What does the OBDII code P1935 mean on a Mercury?

P1935 indicates a "Fuel Additive Level Low" issue, meaning the diesel exhaust fluid (DEF) or fuel additive reservoir is below the minimum level required for proper operation.

2. What are the common symptoms of code P1935 in a Mercury vehicle?

Typical symptoms include a warning light on the dashboard, reduced engine performance, or the vehicle entering limp mode.

3. What causes code P1935 to appear on a Mercury?

Common causes include a low level of fuel additive or DEF, a faulty additive level sensor, wiring issues, or a malfunctioning additive pump.

4. Can I drive my Mercury with the P1935 code active?

Driving with the P1935 code may cause reduced engine performance, and ignoring it for too long could lead to further emissions system issues.

5. How do I fix the P1935 code on my Mercury?

Start by refilling the fuel additive or DEF tank. If the code persists, inspect the level sensor, wiring, and pump for faults.

6. How do I check the fuel additive or DEF level in a Mercury?

Many Mercury vehicles display DEF or additive levels on the dashboard. If not, consult the owner’s manual or use a diagnostic scan tool.

7. What tools are needed to diagnose the P1935 code in a Mercury?

A compatible OBDII scanner can help check for the code, and a multimeter may be needed to test the sensor and wiring.

8. Is the P1935 code related to diesel engines only?

Yes, P1935 is specific to diesel engines that use a fuel additive or DEF system for emissions control.

9. How much does it typically cost to fix the P1935 code on a Mercury?

Costs vary but refilling the additive tank typically ranges from $10-$50, while sensor or pump repairs may cost $100-$300 or more.

10. Can a faulty additive level sensor trigger code P1935 on a Mercury?

Yes, a malfunctioning additive level sensor is a common cause of the P1935 code.

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