P00B7: Coolant flow through the engine cooling system lower than the computer expects

Engine coolant flow low / performance

Severity: Severity not verified — if the car runs badly, have it inspected

The code reports low coolant flow, which can lead to overheating, but the sources read do not grade the risk and the cause ranges from software to a stuck thermostat or pump. Owner complaints include overheating, so treat a hot engine as serious.

It gets more serious if:

Inspect soon: Get it inspected soon if the temperature gauge rises, a coolant warning shows, or the engine loses power. One 2024 Volkswagen complaint and one 2018 Alfa Romeo complaint report these with P00B7 stored.

Source: how we rate severity

P00B7 in short

P00B7 means the engine computer thinks coolant is not flowing as well as it should. The usual causes are low coolant, a stuck thermostat or a failing coolant pump or valve. Volkswagen has a bulletin that fixes it with a software update on some models, so ask a dealer to check before replacing parts.

The computer compares coolant temperature behaviour with what it expects for the flow it commands. TroubleCodes.net gives the title as engine coolant flow low or performance, and says it can come from low coolant or a stuck flow valve.

The cause depends on the vehicle. On a Chevrolet Colorado complaint, the code was read as coolant flow restriction and the repair was a thermostat and coolant flush. On a Volkswagen Golf R complaint, the dealer diagnosed the thermostat housing. TroubleCodes.net describes the code for the Chevrolet Volt, where it points to the battery cooling circuit.

A Volkswagen Atlas Cross Sport complaint says the repair order cites Volkswagen bulletin 01-24-06 for P00B7, P0116 or P2681, and that the dealer fixed it with an engine computer programming update. This file did not read the bulletin itself, only the owner's account.

Most likely causes

Cause 1: Stuck or faulty thermostat or thermostat housing
Supported by vehicle data
Why it ranks here
Owner complaints on a 2016 Chevrolet Colorado (ODI 11575521) and 2017 Volkswagen Golf R (ODI 11561868) tie the code to a stuck thermostat or thermostat housing.
What would change this
Rises if the engine is slow to warm or the temperature reading is erratic. Falls if a thermostat test shows it opening normally.
How to test the thermostat
Cause 2: Low coolant, a blocked passage or a failing pump or flow valve
Common general cause
Why it ranks here
TroubleCodes.net lists low coolant, a stuck coolant flow control valve, temperature sensors and the coolant pump as causes.
What would change this
Rises if the coolant is low or a pump or valve does not respond. Falls if coolant and flow check out.
Cause 3: Engine computer programming (some Volkswagen models)
Possible — needs testing
Why it ranks here
An owner complaint on a 2024 Atlas Cross Sport (ODI 11756349) says a dealer cleared the code with a computer update under bulletin 01-24-06. Only the owner's account was read.
What would change this
Rises if a dealer finds your VIN covered and the software out of date. Falls if the computer is already current.
How to test the engine control module (ecm / pcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

Step 1: Read all stored codes with a scan tool, noting temperature, thermostat or coolant pump codes stored with P00B7.
Low riskTool: OBD-II scan tool
- IfOther cooling codes are stored
  It meansWork on those first, they may share a cause.
  Go to step 2
- IfP00B7 is alone
  It meansCheck the coolant next.
  Go to step 2
Step 2: With the engine off and fully cool, check the coolant level in the reservoir and look for leaks or crusty coolant stains.
Low risk
- IfThe level is low or there are leaks
  It meansFind the leak and restore the level before testing anything else.
  Points to: Low coolant, a blocked passage or a failing pump or flow valve
- IfThe level is correct
  It meansAsk a dealer about software updates, then test the thermostat.
  Go to step 3
Step 3: Have a shop watch the coolant temperature through warm-up on a scan tool and test the thermostat and, where fitted, the coolant pump or flow valve.
Best left to a shopTool: scan tool with live data
Warning:Cooling system parts are hot and pressurised after the engine has run, and opening the cap can scald. Let a shop do this on a cool engine.
- IfThe thermostat sticks or the temperature behaves erratically
  It meansThe thermostat or housing is at fault.
  Points to: Stuck or faulty thermostat or thermostat housing
- IfThe pump or valve does not respond or flow is poor
  It meansThe pump or flow valve is suspect.
  Points to: Low coolant, a blocked passage or a failing pump or flow valve
- IfThe cooling parts test fine
  It meansAsk whether a software update applies to your vehicle.
  Points to: Engine computer programming (some Volkswagen models)

Symptoms

Check engine light on
Temperature reading erratic or cooling fans running hard
Engine overheating, a coolant warning, or loss of power Gets more serious: stop and have it checked.

How to fix

Parts and cost context

Thermostat:On the owner reports read, a stuck thermostat or housing was one repair. Labour and parts vary by engine; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

2016 · Colorado
Supported by vehicle data
An owner complaint (ODI 11575521) lists P00B7 as coolant flow restriction with a stuck thermostat, repaired by a thermostat and coolant flush. One owner report only.

Volkswagen

2017 · Golf R
Supported by vehicle data
An owner complaint (ODI 11561868) reports P00B7 with a dealer diagnosis of a faulty thermostat and housing. One owner report only.
2024 · Atlas Cross Sport
Supported by vehicle data
An owner complaint (ODI 11756349) says the dealer used Volkswagen bulletin 01-24-06 for P00B7, P0116 or P2681 and updated the engine computer. The bulletin itself was not read.

No curated relationships for P00B7 yet.

All Engine cooling (thermostat) codes

P00B7 questions

Is P00B7 only for the Chevrolet Volt?

TroubleCodes.net describes it for the Volt, but owner complaints show it on a Chevrolet Colorado, Volkswagen and Alfa Romeo too, where the cause was the engine cooling system.

Sources and review

P0119, P00B7 and P0129 trouble code pages — TroubleCodes.net
NHTSA owner complaints naming P0119 (ODI 10484858, 10714028), P0129 (ODI 10321868, 10496081, 10551947, 10567604) and P00B7 (ODI 11561868, 11575521, 11756349, 11768539) — NHTSA Office of Defects Investigation

Last reviewed: October 16, 2026
Written by: Saurabh K.
Editorial review: Pending
Technician review: Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

Severity: Severity not verified — if the car runs badly, have it inspected

Most likely causes

Cause 1: Stuck or faulty thermostat or thermostat housing

Cause 2: Low coolant, a blocked passage or a failing pump or flow valve

Cause 3: Engine computer programming (some Volkswagen models)

What to test first

Step 1: Read all stored codes with a scan tool, noting temperature, thermostat or coolant pump codes stored with P00B7.

Step 2: With the engine off and fully cool, check the coolant level in the reservoir and look for leaks or crusty coolant stains.

Step 3: Have a shop watch the coolant temperature through warm-up on a scan tool and test the thermostat and, where fitted, the coolant pump or flow valve.