diff --git a/src/parser.c b/src/parser.c
index 98d2c89..9fdb1a9 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -149,10 +149,10 @@ dc_parser_new_internal (dc_parser_t **out, dc_context_t *context, dc_family_t fa
 		rc = atomics_cobalt_parser_create (&parser, context);
 		break;
 	case DC_FAMILY_SHEARWATER_PREDATOR:
-		rc = shearwater_predator_parser_create (&parser, context);
+		rc = shearwater_predator_parser_create (&parser, context, model);
 		break;
 	case DC_FAMILY_SHEARWATER_PETREL:
-		rc = shearwater_petrel_parser_create (&parser, context);
+		rc = shearwater_petrel_parser_create (&parser, context, model);
 		break;
 	case DC_FAMILY_DIVERITE_NITEKQ:
 		rc = diverite_nitekq_parser_create (&parser, context);
diff --git a/src/shearwater_petrel.h b/src/shearwater_petrel.h
index 8b927d6..c23bb74 100644
--- a/src/shearwater_petrel.h
+++ b/src/shearwater_petrel.h
@@ -34,7 +34,7 @@ dc_status_t
 shearwater_petrel_device_open (dc_device_t **device, dc_context_t *context, const char *name);
 
 dc_status_t
-shearwater_petrel_parser_create (dc_parser_t **parser, dc_context_t *context);
+shearwater_petrel_parser_create (dc_parser_t **parser, dc_context_t *context, unsigned int model);
 
 #ifdef __cplusplus
 }
diff --git a/src/shearwater_predator.h b/src/shearwater_predator.h
index f21d445..4665f80 100644
--- a/src/shearwater_predator.h
+++ b/src/shearwater_predator.h
@@ -34,7 +34,7 @@ dc_status_t
 shearwater_predator_device_open (dc_device_t **device, dc_context_t *context, const char *name);
 
 dc_status_t
-shearwater_predator_parser_create (dc_parser_t **parser, dc_context_t *context);
+shearwater_predator_parser_create (dc_parser_t **parser, dc_context_t *context, unsigned int model);
 
 #ifdef __cplusplus
 }
diff --git a/src/shearwater_predator_parser.c b/src/shearwater_predator_parser.c
index 039926f..e922220 100644
--- a/src/shearwater_predator_parser.c
+++ b/src/shearwater_predator_parser.c
@@ -48,10 +48,14 @@
 
 #define NGASMIXES 10
 
+#define PREDATOR 2
+#define PETREL   3
+
 typedef struct shearwater_predator_parser_t shearwater_predator_parser_t;
 
 struct shearwater_predator_parser_t {
 	dc_parser_t base;
+	unsigned int model;
 	unsigned int petrel;
 	unsigned int samplesize;
 	// Cached fields.
@@ -61,6 +65,7 @@ struct shearwater_predator_parser_t {
 	unsigned int ngasmixes;
 	unsigned int oxygen[NGASMIXES];
 	unsigned int helium[NGASMIXES];
+	double calibration[3];
 	dc_divemode_t mode;
 };
 
@@ -105,7 +110,7 @@ shearwater_predator_find_gasmix (shearwater_predator_parser_t *parser, unsigned
 
 
 static dc_status_t
-shearwater_common_parser_create (dc_parser_t **out, dc_context_t *context, unsigned int petrel)
+shearwater_common_parser_create (dc_parser_t **out, dc_context_t *context, unsigned int model, unsigned int petrel)
 {
 	shearwater_predator_parser_t *parser = NULL;
 	const dc_parser_vtable_t *vtable = NULL;
@@ -130,6 +135,7 @@ shearwater_common_parser_create (dc_parser_t **out, dc_context_t *context, unsig
 	}
 
 	// Set the default values.
+	parser->model = model;
 	parser->petrel = petrel;
 	parser->samplesize = samplesize;
 	parser->cached = 0;
@@ -149,16 +155,16 @@ shearwater_common_parser_create (dc_parser_t **out, dc_context_t *context, unsig
 
 
 dc_status_t
-shearwater_predator_parser_create (dc_parser_t **out, dc_context_t *context)
+shearwater_predator_parser_create (dc_parser_t **out, dc_context_t *context, unsigned int model)
 {
-	return shearwater_common_parser_create (out, context, 0);
+	return shearwater_common_parser_create (out, context, model, 0);
 }
 
 
 dc_status_t
-shearwater_petrel_parser_create (dc_parser_t **out, dc_context_t *context)
+shearwater_petrel_parser_create (dc_parser_t **out, dc_context_t *context, unsigned int model)
 {
-	return shearwater_common_parser_create (out, context, 1);
+	return shearwater_common_parser_create (out, context, model, 1);
 }
 
 
@@ -281,6 +287,20 @@ shearwater_predator_parser_cache (shearwater_predator_parser_t *parser)
 		offset += parser->samplesize;
 	}
 
+	// Cache sensor calibration for later use
+	parser->calibration[0] = array_uint16_be(data + 87) / 100000.0;
+	parser->calibration[1] = array_uint16_be(data + 89) / 100000.0;
+	parser->calibration[2] = array_uint16_be(data + 91) / 100000.0;
+	// The Predator expects the mV output of the cells to be within 30mV
+	// to 70mV in 100% O2 at 1 atmosphere.
+	// If the calibration value is scaled with a factor 2.2, then the
+	// sensors lines up and matches the average.
+	if (parser->model == PREDATOR) {
+		for (size_t i = 0; i < 3; ++i) {
+			parser->calibration[i] *= 2.2;
+		}
+	}
+
 	// Cache the data for later use.
 	parser->headersize = headersize;
 	parser->footersize = footersize;
@@ -422,11 +442,24 @@ shearwater_predator_parser_samples_foreach (dc_parser_t *abstract, dc_sample_cal
 		// Status flags.
 		unsigned int status = data[offset + 11];
 
-		// PPO2
-		sample.ppo2 = data[offset + 6] / 100.0;
-		if (callback) callback (DC_SAMPLE_PPO2, sample, userdata);
-
 		if ((status & OC) == 0) {
+			// PPO2
+#ifdef SENSOR_AVERAGE
+			sample.ppo2 = data[offset + 6] / 100.0;
+			if (callback) callback (DC_SAMPLE_PPO2, sample, userdata);
+#else
+			if ((status & PPO2_EXTERNAL) == 0) {
+				sample.ppo2 = data[offset + 12] * parser->calibration[0];
+				if (callback && (data[86] & 0x01)) callback (DC_SAMPLE_PPO2, sample, userdata);
+
+				sample.ppo2 = data[offset + 14] * parser->calibration[1];
+				if (callback && (data[86] & 0x02)) callback (DC_SAMPLE_PPO2, sample, userdata);
+
+				sample.ppo2 = data[offset + 15] * parser->calibration[2];
+				if (callback && (data[86] & 0x04)) callback (DC_SAMPLE_PPO2, sample, userdata);
+			}
+#endif
+
 			// Setpoint
 			if (parser->petrel) {
 				sample.setpoint = data[offset + 18] / 100.0;