P20EE on DS: causes, affected engines and fix

Documented faults in DS engines that can trigger P20EE

Grouped by engine or model, from most to least important. These are faults with AdBlue and with the particulate filter: not all of them will necessarily set the code, and only a diagnosis confirms the cause on your car.

1.6 HDi

In DS 3, DS 4 I and DS 5

- Medium severityFrequency: Very frequentEmissions controlAdBlue tank and pump fault (1.6 BlueHDi)The 1.6 BlueHDi engines (2013-2019) suffer from the AdBlue tank defect of Stellantis diesels: an emissions warning appears with a countdown until starting is prevented. Replacing the tank, with the integrated pump, costs over €1,000 (price in Spain), but there is an extended warranty of up to 8 years.Repair: €1,000–€1,200
- Medium severityFrequency: CommonEmissions controlAdditive-fed particulate filter (Eolys cerine): depleted additive and cloggingThe DPF on the 1.6 HDi and BlueHDi works with an additive (cerine) that runs out at 80,000-120,000 km and has to be topped up for around €100-120 (price in Spain). With a lot of town use the filter clogs and the warning appears; if it is left, a new DPF costs around €1,500.Repair (garage): €100–€1,500Appears at around 80,000 km

2.0 BlueHDi

In DS 7 Crossback

1.5 BlueHDi

In DS 3 Crossback and DS 7 Crossback

- Medium severityFrequency: Very frequentEmissions controlAdBlue tank and pump failure1.5 BlueHDi engines built up to August 2020 can suffer failures of the AdBlue tank pump module, with a "no engine start" countdown. The whole tank is usually replaced and Stellantis contributes to the cost up to 8 years.Repair: €1,000–€1,500

Common causes of P20EE on any make

From most to least likely, according to the sources.

1Poor-quality AdBlue, with an incorrect concentration or the wrong fluid in the tank.^[1][2][3]
2Insufficient or interrupted dosing: faulty, blocked or urea-crystallised injector or dosing module, especially on cars that make short journeys.^[1][3][4]
3Faulty NOx sensors, or ones that have lost accuracy, before or after the catalyst.^[1][2][4]
4Exhaust leaks upstream of the SCR catalyst, which distort the measurement.^[1][2]

What to check first

The first diagnostic steps, from the most likely and cheapest to check to the most expensive.

1Read all the codes. If there is also a NOx sensor code, diagnose it first: a drifting sensor or a leak near the sensor distorts the conversion reading.^[1][3]
2Check the AdBlue: that it is fresh and of the correct specification (ISO 22241 standard) and, if you can, measure its concentration with a refractometer, which should be around 32.5% urea.^[1][3][4]
3Verify the operation and dosing of the system: check the injector or dosing module (crystals, blockages) and carry out the flow test specified by the manufacturer, which measures how much AdBlue it actually injects in a given time.^[1][3]

Full guide to P20EE: symptoms, diagnosis and whether you can drive

Frequently asked questions

Which DS engines have faults that can trigger P20EE?

1.6 HDi (2 faults), 2.0 BlueHDi (2 faults) and 1.5 BlueHDi (1 fault). Each fault has its own page with the affected years and versions, the symptoms and the repair cost.

What does code P20EE mean on a DS?

SCR NOx catalyst efficiency below threshold (bank 1). The SCR system reduces nitrogen oxides (NOx) on diesels by injecting AdBlue into the exhaust: the urea breaks down into ammonia, which reacts with the NOx in the SCR catalyst and converts it into nitrogen and water vapour. One NOx sensor before the catalyst and another after it let the control unit check how much is being converted. It is a generic OBD-II code: it means the same on a DS as on any other make.^[1][2][3][4]

Can I keep driving with P20EE?

Garage soon. The sources do not set an exact time limit. Ross-Tech says there may be loss of power or limp mode, and Fleet Rabbit that the engine reduces its power, at a point that depends on each engine's calibration. RACE adds that if AdBlue runs out or a component of the system fails, the car may show warnings and even prevent a restart. It does not usually force you to stop on the spot, but it should be diagnosed soon, before the car starts to limit performance.^[1][3][4]

Sources

Every fact on this page links to its source. If you find an error, let us know.

P20EE/008430 - SCR NOx Catalyst Bank 1: Efficiency too LowRoss-Tech · Technical documentation · consulted 2 October 2026
PartsAvatar.ca - Generic Car OBD Error Code P20EEPartsAvatar · Technical documentation · published 2 June 2022 · consulted 2 October 2026
SCR & DEF Codes Explained: P20EE, P207F, P20E8 Complete Fleet GuideFleetRabbit · Other source · published 23 September 2026 · consulted 2 October 2026
Qué es un catalizador SCR: funcionamiento, AdBlue y mantenimientoRACE · Motoring press · published 23 September 2026 · consulted 2 October 2026 · in Spanish