P20E4 code meaning
Exhaust Gas Temperature Sensor 2/3 Correlation (Bank 1)
Powertrain system Generic code P20xx codes Check engine light
What P20E4 means
P20E4 covers the pair around the particulate filter: sensor 2 at the filter inlet and sensor 3 at its outlet on bank 1 no longer agree. GM documents the code for the diesel in table 15OBDG04 (also 14OBDG04): after a soak of at least 28,800 s the start-up values of the filter upstream and downstream sensors are compared against a look-up limit, and a larger gap is a Type B fault. Because both sensors steer and protect filter regeneration, a biased one can lead to regenerations that run too cool or too hot. P20E2 covers the pair around the oxidation catalyst, while P2084 and P242B report range faults of a single sensor. The patent US7533519 uses the same inlet/outlet arrangement for its stuck-in-range test. Drivers usually see the MIL and may notice more frequent or aborted regenerations.
P20E4 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P20E4
- Malfunction indicator lamp on
- Regenerations aborted or happening more often
- Filter loading warning in some vehicles
Common causes of P20E4
- Most likelyFilter inlet or outlet temperature sensor aged by heat cycling
- PossibleHeat-damaged or corroded sensor connector or lead
- Less likelyHeavy soot or ash deposits on a sensor tip slowing its response
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Exhaust gas temperature sensorWiring harness
What each part of P20E4 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. |
| E4 | The exact fault in that area. |
What to do next
- Note P20E4 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 P20E4
What does P20E4 mean?
P20E4 means "Exhaust Gas Temperature Sensor 2/3 Correlation (Bank 1)". P20E4 covers the pair around the particulate filter: sensor 2 at the filter inlet and sensor 3 at its outlet on bank 1 no longer agree. It is a generic code, so it means the same on every make.
Is it safe to drive with P20E4?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P20E4 fail an emissions test?
Yes, it can. P20E4 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 P20E4 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P20E4 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.