P00B6 medium Severity

P00B6: Radiator Coolant Temperature/Engine Coolant Temperature Correlation

May cause poor idle, reduced fuel economy, potential overheating and degraded engine performance

Overview

P00B6 is a generic OBD-II DTC indicating a correlation fault between radiator coolant temperature (RCT) and engine coolant temperature (ECT) sensor readings when the difference exceeds manufacturer thresholds

Common Symptoms

  • Check Engine Light (MIL) illumination
  • Poor idle quality
  • Reduced fuel economy
  • Inconsistent or abnormal coolant temperature readings
  • Potential engine overheating or cooling fan running constantly

Most Common Causes

Faulty engine coolant temperature (ECT) sensor high

ECT provides primary coolant temp data; erroneous readings frequently trigger this correlation code

Faulty radiator coolant temperature (RCT) sensor high

Incorrect RCT readings directly contribute to correlation mismatch

Low coolant level or air in cooling system medium

Poor coolant flow can skew temperature differentials between sensors

Wiring or connector faults between sensors and PCM medium

Open, shorted, corroded wiring or poor grounds can distort sensor signals

PCM fault or software issue low

Rare but possible if sensor circuits and data are verified good

Diagnostic Steps

  1. Verify fault code presence and clear codes; perform a test drive to confirm reappearance
    Expected: P00B6 reoccurs under normal engine temperature conditions
    Interpretation: Confirms persistent correlation fault
  2. Inspect coolant level and cooling system for leaks or air pockets
    Expected: Coolant level at proper fill; no air in system
    Interpretation: Rules out coolant level/flow issues
  3. Visually inspect ECT and RCT sensor connectors and wiring for damage/corrosion
    Expected: Connectors intact and wiring undamaged
    Interpretation: If damaged, repair/replace wiring before further sensor testing
  4. Measure voltage/resistance of ECT and RCT sensors and compare to manufacturer specs
    Expected: Sensor readings change consistently with temperature
    Interpretation: Out-of-spec sensors should be replaced
  5. Using scan data, compare real-time ECT and RCT values with measured temperatures via infrared thermometer
    Expected: Sensor reported values correspond to actual temperatures
    Interpretation: Discrepancies indicate sensor or circuit fault

Repair Solutions

Replace faulty engine coolant temperature (ECT) sensor medium
Estimated Cost: $50 - $150

Typical cost for sensor and labor; vary by vehicle model

Replace faulty radiator coolant temperature (RCT) sensor medium
Estimated Cost: $50 - $150

Sensor cost plus labor; ensure proper part for vehicle

Repair or replace damaged wiring/connectors medium
Estimated Cost: $20 - $200

Costs depend on extent of wiring damage

Flush and refill coolant, bleed air from system easy
Estimated Cost: $30 - $120

May resolve minor flow discrepancies

PCM reprogramming or replacement hard
Estimated Cost: $300 - $1200

Only after excluding all sensor and wiring issues

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Assuming a bad PCM before verifying sensors and wiring
  • Replacing only one sensor when both should be tested
  • Ignoring low coolant level as a contributing factor

Frequently Asked Questions

Can you explain the meaning of P00B6?

When your OBD-II scanner reads P00B6, it means: Radiator Coolant Temperature/Engine Coolant Temperature Correlation. This code is related to the vehicle's Sensors.

Should I stop driving if I have P00B6?

The P00B6 code is considered medium severity. May cause poor idle, reduced fuel economy, potential overheating and degraded engine performance

What are the symptoms of P00B6?

Common symptoms include: Check Engine Light (MIL) illumination, Poor idle quality, Reduced fuel economy. You might also notice the Check Engine Light is on.

Potential causes for OBDII code P00B6

The most common causes are: Faulty engine coolant temperature (ECT) sensor, Faulty radiator coolant temperature (RCT) sensor, Low coolant level or air in cooling system.

Estimated repair costs for different causes of P00B6

The cost varies significantly based on the root cause. For example, replacing a Flush and refill coolant, bleed air from system typically costs between $30 and $120, while fixing a PCM reprogramming or replacement can range from $300 to $1200.

Is the P00B6 code specific to Ford?

This is a universal code. You might see P00B6 on Ford, Chevrolet, Toyota, Honda, Nissan, or any other OBD-II vehicle.

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