P20F5 code meaning
Reductant Consumption Too High
Powertrain system Generic code P20xx codes Check engine light
What P20F5 means
P20F5 is set when more diesel exhaust fluid is used, or has to be corrected away, than the control unit planned. In VW's 2014 Touareg TDI data book the trigger is an SCR adaptation value of 0.51 or lower: the NOx feedback keeps cutting the commanded dose because more fluid evidently reaches the catalyst than intended. GM maps the same idea to P249E (factor below 0.41, Type B). Likely reasons are a dosing valve that drips or does not close fully, an external leak downstream of the pressure sensor that empties the tank faster, or a pressure sensor reading low so the pump overdelivers. Jeep lists P20F5 with P20F4 on the 2.2 L diesel Cherokee and cures both with dosing unit software (18-088-20). An Isuzu patent also aims at a valve that keeps spraying. Overdosing risks ammonia slip and deposits.
P20F5 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P20F5
- Check engine light and DEF warning
- DEF tank empties faster than usual, white crust around the dosing valve
- Ammonia smell or deposits in the exhaust
Common causes of P20F5
- Most likelyDosing valve dripping or not sealing between pulses
- PossibleExternal leak at the valve or its supply line
- Less likelyPressure sensor reading low, causing excess delivery
- Less likelyDosing control unit software requiring an update
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Reductant injection valveReductant supply lineReductant pressure control valve
What each part of P20F5 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| F5 | The exact fault in that area. |
What to do next
- Note P20F5 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P20F5
What does P20F5 mean?
P20F5 means "Reductant Consumption Too High". P20F5 is set when more diesel exhaust fluid is used, or has to be corrected away, than the control unit planned. It is a generic code, so it means the same on every make.
Is it safe to drive with P20F5?
Drive gently and only to a workshop. With P20F5 the car can go into limp mode (reduced power) to protect itself.
Will P20F5 fail an emissions test?
Yes, it can. P20F5 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P20F5 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P20F5 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.