Insufficient egr flow. Cooling fan does not run

Hi Joe

Like all solenoid valves, you can clean them with throttle body cleaner and then test the solenoid electronically with a 12 volt supply.

P0401 Exhaust EGR Flow Insufficient

Toyota Nation Forum https://www.toyotanation.com > threads > p0401-exha...
May 1, 2014 - The sensor is how the ECM determines there's insufficient EGR flow. It's on the intake-side of the system and if not enough exhaust-gases flow ...

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P0401 : EGR Flow Insufficient on 1996 Toyota Corolla

OBD-Codes.com https://www.obd-codes.com > forums > viewtopic
Jan 20, 2007 - on EGR codes, we recommend replacing the EGR, vacuum modulator and VSV (if equipped) and cleaning out the carbon buildup to the intake from the ...
If that finds nothing wrong, remove the EGR valve and bypass tube and check them for cleanliness and blockages. If they are blocked, follow your maintenance manual's instructions for cleaning them out so you do not damage the valve, then replace them and reset the ECM.

Insufficient EGR Flow - P0401 Code - Toyota

If all is ok at normal road speeds and overheating only occurs when stationary at idle it indicates insufficient cooling air being drawn through the radiator by the cooling fan, insufficient coolant circulation or both.
Some waterpumps have a plastic impeller that sometimes loses a blade, radiators can become partially blocked with mud and insects and sometimes during repairs a radiator mask is left off for added convenience with the result the fan draws air through almost everywhere except the radiator.

It would be wise to monitor coolant flow during idle to ensure it remains constant - if the degassing system had become blocked or overloaded it could cause the thermostat to close.

Depends on the year,make,model and engine size to determine the reason for the insufficient EGR flow which sets a p0401 engine code. If it is a Ford vehicle the most common failure is a bad DPFE sensor. If it is a GM vehicle with an electronic EGR valve, the valve is usually bad. Most imports use a EGR temp sensor which ends up being a bad sensor or vacuum line to the valve. Send me more info and I will be glad to help you fix the problem.

the exhaust path there must be clear
end to end, its NOT air that is EGR fail for exh. flow, for EGR only.
which engine, ?????
no 2 engines made use the same flow.
so..........????????

P0401 - Exhaust Gas Recirculation Flow Insufficient Detected

Possible causes - Harness or connectors (EGR volume control valve circuit is open or shorted.)
- EGR volume control valve stuck closed
- EGR volume control solenoid valve
- Dead (Weak) battery
- EGR passage clogged
- Exhaust gas leaks Possible solution - Clean EGR Valve
- Repair EGR harness or connector
- Replaced EGR volume control solenoid valve
- Replaced EGR volume control valve

1. po401 refers to an insuffient flow of EGR gasses
2. locate egr valve
3. with engine running at idle
4. on the underside of the valve you can access the diaphram.
5. wearing glove if ness
6. lift diaphram while idling
7. does engine stall or run very rough?
8. if not remove valve
9. start engine
10. you should hear a very large vaccum leak and exhaust noise
11. if either are missing investigate cause
12. if ok reassemble.
13. locate DPFE sensor
14. inspect sensor for damage
15. inspect hose to sensor for damage
16. replace sensor

PO-401
EGR Flow Insufficient Detected

clean the exhaust ports where the egr valve fastens to the tube and check the EGR valve for being out of range sounds like is it defective

the code you have may not be due to insufficient lift, more likely you have either high or low voltage running through egr. replace the valve and your issues should go away.

i found that the egr valves sometimes get clogged up with carbon and can be remedied by removing the valve and scraping the port clean .