What does fault code ECM-P208021 mean?

Diagnostic fault code details for ECM-P208021 (Volvo S60 (2011–), Volvo S80 (2007–), Volvo V40 (2013–)). Repair service at OBD Tuning.

VOLVO

ECM-P208021 - Exhaust Gas Temperature Sensor Circuit Range/Performance Bank 1 Sensor 1. General Signal Failures. Signal too low

System

Engine Control Module (ECM)

Volvo models this fault code applies to

Applies to the following models:

8 models

S60 (2011–), S80 (2007–), V40 (2013–), V40 Cross Country (2013–), V60 (2011–), V70 (2008–), XC60 (2009–), XC70 (2008–)

Show models by year and engine (8)

What does this fault code mean?

The code is set when the reading from the temperature sensor ahead of the catalytic converter departs from the calculated value. The engine control module monitors this, and it can result from a loose or oxidised connection, a short to ground in the signal wire or a damaged sensor. An incorrect reading from the mass air flow meter can also trigger it.

Possible causes

Loose connection or oxidation in the connections
Short circuit to ground in the signal wire
Damaged exhaust temperature sensor before the catalytic converter
The mass air flow meter gives an incorrect reading, for example because of charge air leakage

What you can do

1If you have a diagnostic tool: start the engine and read the sensor value in live data, and check that it is stable while the engine runs
2Check that the connectors to the sensor are secure and free from oxidation
3Use a multimeter to check that the signal wire has no short circuit to ground
4Check that the charge air system does not leak, since a leak can give the mass air flow meter a wrong reading
5If the fault remains, have a workshop with diagnostic equipment check the sensor

Symptoms you may notice1

Check engine warning lamp lights or behaves abnormally

What the fault can affect1

A calculated value is used instead of the sensor signal

General guidance for car owners. Diagnosis on the car can point to a different cause.