Honeywell PM Sensor Project, ICAT 2008

This page updated March 3, 2009

Honeywell Laboratories

Demonstration of Particulate Matter (PM) Sensor in post-DPF

Technology and Innovation
Honeywell International proposes to develop a particulate matter (PM) sensor to assist the OBD system of a diesel engine in monitoring compliance with proposed particulate matter exhaust limits of 0.03 g/BHP*hr as identified in California Code of Regulations, Title 13, Section 1971.1(e)(8). The sensor would provide a direct correlation to the level of particulate matter exiting the after-treatment system as opposed to more conventional indirect methods of determining the proper operation of the DPF which is assumed to effectively reduce the PM emissions if intact. The PM sensor could be used alone or in conjunction with existing monitored engine and after-treatment parameters as input(s) to the OBD system. Customers for such a sensor would include both engine OEMs and after-treatment systems providers that serve the retrofit market.

The PM sensor operates under the basic premise of measuring the charge on particles inherent from the combustion process in the cylinder. The combustion process has been shown to electrically charge particulate effluents (1, 2). It has also been shown that these charges are representative of mass of particulates in exhaust stream (3,4), and can create a signal in the PM sensor that is related to the mass of carbon particles in the exhaust stream. The PM sensor has been tested on-engine upstream of the DPF and the results of that testing have indicated that the sensor has a proportional response to DPF loading rate.
Emission Benefit
The proposed PM sensor for the diesel vehicle OBD application, illustrated in Figure 3, provides a cost-effective means of monitoring the effectiveness of diesel particulate filters (DPF) in preventing the emission of soot. If the sensor detects that the level of PM passing beyond the DPF into the tailpipe exceeds the OBD threshold of 0.03 g/bhp-hr the OBD system will take action. The OBD will determine if the DPF meets compliance standards or has failed and will perform self-check diagnostics to detect PM sensor failure as well.
The successful commercialization of the PM sensor enables direct measurement of the diesel particulate in the exhaust, and when coupled to the OBD system will alert the driver of a compliance failure, such that corrective action can be taken. In the absence of this kind of precision, non-compliant diesels will be undetected and will continue to operate on the roads.  This sensor will enable the emissions reduction targets of the regulations are in-fact verifiably enforced.
Project Description
This program will conduct on-engine testing of Honeywell’s PM sensor within the post-DPF environment. The tests will examine the probe responsiveness and signal accuracy by comparing with calibrated particle measuring equipment and by confirmation with gravimetric measurements during a modified Supplemental Emissions Test (SET). The probe response will be determined in a post-DPF environment using both a functional DPF and also through failing the DPF to provide the DPF conditions which will result in post-DPF particle levels that will approach the 3x certification levels of 0.03 gm/bhp-hr. To minimize the amount of testing required on this program, the testing will be done on a representative subset of the SET tests whose operating points generate PM levels which span the PM range from below to above the OBD threshold. The data from these measurements will be analyzed to provide the correlation of the PM sensor output with both particle and charge distributions in addition to correlation with the gravimetric measurements. These results will be provided to CARB as the deliverables from this study.

Funding Source

Funding Amount



Grantee & Partners


ICAT Funded Projects