AutoFixDB - Free OBD-II diagnostic trouble code lookup. Find causes, symptoms, diagnostic steps and repair solutions.

Overview

DTC P0187 indicates a low input signal from the Fuel Temperature Sensor 'B' circuit, where the PCM/ECM detects voltage below expected thresholds, often due to sensor failure or electrical issues.

Common Symptoms

Check Engine Light illuminated
Reduced engine performance or hesitation
Increased fuel consumption
Rough idle or stalling
Difficulty starting the engine

Most Common Causes

Faulty fuel temperature sensor 'B' high

Sensor internal failure or incorrect resistance causing low voltage signal to PCM

Wiring or connector issues (opens, corrosion, shorts) high

Damaged harness or poor connections often result in low circuit input

Poor ground or reference voltage at sensor circuit medium

Loss of proper reference voltage can mimic sensor failure

PCM/ECU malfunction or software error low

Rare but possible when wiring and sensor test good yet code persists

Diagnostic Steps

Connect a professional OBD-II scanner and confirm P0187 and any related trouble codes

Expected: P0187 present, note freeze frame and related codes

Interpretation: Establish baseline before repairs
Perform visual inspection of fuel temperature sensor 'B' wiring harness and connectors

Expected: Check for corrosion, damage, loose pins

Interpretation: Mechanical issues in wiring can produce low input signal
Backprobe sensor connector and test reference voltage, signal, and ground with multimeter

Expected: Reference voltage present (typically ~5V), signal within expected range

Interpretation: No reference or poor ground suggests wiring/ECU issue
Test sensor resistance and operation per manufacturer spec

Expected: Resistance changes with temperature consistent with specs

Interpretation: Out-of-spec indicates faulty sensor
Clear codes and perform a test drive after repairs

Expected: No reoccurrence of P0187

Interpretation: Successful repair

Repair Solutions

Replace fuel temperature sensor 'B' medium

Estimated Cost: $100 - $300

OEM or equivalent sensor recommended; costs vary by vehicle

Repair or replace damaged wiring/connectors medium

Estimated Cost: $20 - $150

Includes labor and materials; ensure solid grounds

PCM/ECU reprogramming or replacement hard

Estimated Cost: $200 - $800

Only if wiring and sensor confirmed good

Common Misdiagnoses

Avoid these common diagnostic mistakes:

Random engine performance issues blamed on unrelated sensors instead of verifying fuel temperature signal
Immediate replacement of PCM without verifying wiring and sensor

Frequently Asked Questions

What is the definition of the P0187 engine code?

Technically, the P0187 code represents Fuel Temperature Sensor 'B' Circuit Low Input. It usually points to a fault within the Fuel System.

How serious is the P0187 code?

The P0187 code is considered medium severity. Potential for reduced performance, fuel efficiency issues, and rough running; generally drivable short-term but should be addressed

What are the symptoms of P0187?

Common symptoms include: Check Engine Light illuminated, Reduced engine performance or hesitation, Increased fuel consumption. You might also notice the Check Engine Light is on.

What causes the P0187 code?

This code is frequently triggered by: Faulty fuel temperature sensor 'B', Wiring or connector issues (opens, corrosion, shorts), Poor ground or reference voltage at sensor circuit.

How much does it cost to fix P0187?

Expect to pay around $150 if the issue is a Repair or replace damaged wiring/connectors, but up to $800 if the PCM/ECU reprogramming or replacement needs replacement.

Is the P0187 code specific to Ford?

This is a universal code. You might see P0187 on Ford, Chevrolet, Toyota, Honda, Nissan, or any other OBD-II vehicle.

P0187: Fuel Temperature Sensor 'B' Circuit Low Input